Brand new player and my first character is a Tabaxi Ranger. Really high dexterity and charisma. Slightly above average intelligence, but low wisdom. I'm wondering how best to RP the lower wisdom but still kind of smart character?

Make him intellectual but oblivious. For example he may know a lot about a subject, but he’s not likely to actually notice they’re having the conversation. This can make funny role plays because you’ll just randomly join into the conversation and drop some knowledge bombs, then go blank for a little while.

INT vs WIS is often referred to as 'book smarts vs street smarts.' Or knowledge vs experience. From the description: "Wisdom reflects how attuned you are to the world around you and represents perceptiveness and intuition." So maybe you aren't fast to notice details, but if someone else points out the writing, you know that it's Orcish. Or you can tell what someone did/is planning to do, but can't figure out why. Maybe you rush into situations without thinking, but as soon as someone points out 'hey, we don't actually know X or Y,' you realize 'oh right, bad idea.' Maybe you're a little gullible, or like to think the best of people, but if you've done your research beforehand, you can account for that.

First, welcome to the game. 
I just want to caution you about a low wisdom ranger (depending on what you mean by low). Wisdom is important to many of their abilities. Charisma and intelligence are not. You might want to think about re-arranging some things. 

That said, you should absolutely play the character you want, and if you are having fun, you are doing it right. It just might be you find yourself frustrated if your character isn’t quite as effective as the rest of the party. Like, the wizard might end up better at wizard-ing than you are at ranger-ing.

It may not be a problem at all, depending on your table, and you. And it could end up really fun. I’m just trying to throw out a suggestion since you are a new player, and make sure you are aware and it’s a conscious choice. 

I often play low-wisdom characters as reckless, naive or just a bit oblivious t the world around them (or a combination of all three). Depending on how much you lean into the whole tabaxi-as-cats bit then a low wisdom might be very fitting. Accidentally almost stumbling and tripping over something but managing to save yourself in the last moment with an "I meant to do that" look.

That said, as mentioned wisdom is rather important for Rangers so having it as a dumpstat can be rather detrimental to you.

First of all, my general advice to you is to not dump a stat that is important for your character. Swapping your WIS and CHA would make a world of difference for your character, and unless you plan on multiclassing into Bard, Paladin, Warlock, or Sorcerer, your charisma will just go to waste.

If you must play a low-WIS ranger, you need to make considerations regarding your creation choice. Make sure to steer away from spells like Lightning Arrow and Hail of Thorns that call for a saving throw, and select spells like Cure Wounds and Hunter's Mark that don't use your Wisdom.

As for roleplaying (if you choose to play a low-WIS ranger), I tend to play low-WIS characters as reckless, inexperienced, impatient, or oblivious, and how they are this way depends on their other mental scores. Characters with low wisdom and high INT and CHA are likely to be like insane masterminds, able to be trusted no matter how untrustworthy they truly are. Characters with high INT and low WIS and CHA are likely to be more like mad scientists, preferring to stay out of the crowd and take risky actions without considering what might happen, just for the sake on your goals or knowledge. Characters with low INT and WIS and high CHA are dangerously overconfident or outgoing and trusted even though they're actually mostly annoying or unhelpful. Finally, creatures who are low in all three scores are complete dullards.

Thank you guys for your suggestions. A little more background: I committed to playing for the first time about 24 hours before session one. At the first session we made our characters and started the group coming together process and heading out on our first quest. I made my character very quickly and with very little knowledge. Now that I've had time to research and understand the build, I realize I may have messed up with the low wisdom stat (9). Unfortunately, we've already had that first session, so I don't think I can change up my stats now. Now I need to figure out how to make it work.

You should ask your DM. Many will let things change, especially under the circumstances you describe. Double especially with you being a new player. You might try and lean on that part, saying you never would have done it that way if you’d known how to play the game. 
Honestly, it’s a bit on them for not correcting it when you started. 

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First of all, my general advice to you is to not dump a stat that is important for your character. Swapping your WIS and CHA would make a world of difference for your character, and unless you plan on multiclassing into Bard, Paladin, Warlock, or Sorcerer, your charisma will just go to waste.

If you must play a low-WIS ranger, you need to make considerations regarding your creation choice. Make sure to steer away from spells like Lightning Arrow and Hail of Thorns that call for a saving throw, and select spells like Cure Wounds and Hunter's Mark that don't use your Wisdom.

Cure Wounds also uses your wisdom. /nitpick

+1 on asking the DM. If you've only played a session or two it won't have any impact on the story. Explain that it will make the game more fun to play if you have a character that actually works as it's intended. 

Have fun!

I agree, asking the DM if you can shuffle those scores due to not knowing what you were doing so well at creation.  That said, IMO, Ranger is one class that can get by without a boost to their casting stat, if played primarily as a melee character.  Using spells that don't rely as much on Wis isn't too hard, as there are a lot of cases where casting a spell isn't the most effective thing you can do anyway.  In either case, you can easily have a lot of fun with him/her, playing a low Wisdom character, as mentioned above, they are less world wise and thus prone of misjudging things and misreading things.

Best of luck whatever path you end up following.

One thing to chime in with: If you do change your stats for a better wisdom score, but still like the idea of a charismatic ranger, consider the Fey Wanderer subclass at level 3. They get to use their wisdom for all of the charisma skills.

Quote from Panda_wat >>

First of all, my general advice to you is to not dump a stat that is important for your character. Swapping your WIS and CHA would make a world of difference for your character, and unless you plan on multiclassing into Bard, Paladin, Warlock, or Sorcerer, your charisma will just go to waste.

 He can't multiclass. It would require him to have both a dex and wis of 13 to multiclass. His character is locked in, and stuck, having a bad primary stat for your class is a huge irreversable error. He'll need DM intervention, or to retire the character and make a new one, to fix the situation. His only rules legit option, if he wants to stuck it out, is to really focus on the things he can do despite having a bad primary stat. For ranger that means combat focused. He'll essentially be a worse-fighter that can poorly-cast a small number of spells. If his party isn't terribly optimized he'll survive. Otherwise it'll get old fast, being the weakest and least useful character at the table.

You absolutely can play a low wisdom ranger. Especially if playing a phb beastmaster where your pet can help for alot of wisdom rolls. Wolf gets passive perception of 21 with keen senses.

Still it's not a beginner tactic. I recommend talking to your dm and if your stuck or up for the challenge of a low wisdom ranger  come back and tips can be provided.

Playing a low-Wisdom Ranger is certainly doable, but it does work against some of the Ranger's traditional strengths. Two skills that Rangers are typically relied on for are Perception and Survival, both keyed off Wisdom. Any spells that involve your spell attack bonus, spell save DC, or spell ability modifier are going to be less effective. Only one official Ranger spell involves a spell attack, but the Primal Companion options for Beastmasters in Tasha's Cauldon use your spell attack bonus for their attacks. Lots of spells will make use of your spell save DC, as well as the abilities granted by some subclasses(like the Drakewarden's dragon breath). And plenty of things will use your Wisdom modifier, like any healing spells you use, the temp HP from the Tireless ability, etc. Plenty of spells will still work normally though, including some signature Ranger spells like Hunter's Mark, Pass Without Trace, etc. 

As for roleplaying high-Int & low-Wis, the "book smarts vs street smarts" analogy works pretty well, I tend to look at it as "knowledge vs understanding". But honestly, the old joke about describing the six abilities with tomatoes works pretty well. "Intelligence is knowing that tomato is actually. Wisdom is knowing not to put tomatoes in a fruit salad" :)

Thank you all for the help! I talked to my DM and he’s going to let me change around a few of my stats. I think I finally understand how this Tabaxi Ranger works and her wisdom is now 14. Thank you all for your kind suggestions! I feel a lot more confident and I’m excited to really get to play now!

Good luck!

I love playing low wisdom characters.

One of my favorite ways to do it is to have my character choose to do things that I know as a player are unwise.  Maybe scout too far ahead of the party, or "forget" to check for traps on the door, or assume a campsite will be a safe place to sleep.

Acting impulsively, and being very trusting of people

The main thing is to put a wall between good ideas you have as a player and what the character will think of.

Also, don't worry about having low wisdom holding you back as a ranger.  Most of the best ranger spells, like zephyr strike, hunters mark, and pass without trace, don't care at all what your wisdom is.  Just avoid spells that require an attack roll, or make the opponent make a saving through.  Few ranger have a super high wisdom, so those spells are rarely good anyway.

Your wisdom skills might not be great, maybe you have bad eyesight and wear glasses, or are allergic to trees.  Maybe your dm would let your favorite terrain be cities instead of mountains or forests.

Definitely look into fey trickster at level 3