Greetings all

Can someone please explain to me why my level 1 Ranger has a Bonus Action of Two-Weapon Fighting 

Showing up in the Actions section of my DDB character sheet

It also states that I have 1 Attacks per Action

Two-Weapon Fighting

When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative.

If either weapon has the thrown property, you can throw the weapon, instead of making a melee attack with it.
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Applicable rule for 2-weapon fighting

Thank you as I saw this since asking

But I believe my real question is does every race get a Bonus Action @ level 1?

And, if the Bonus Action is stated to be Two-Weapon Fighting… 

Does this mean PC gets to roll their attacks twice should they choose to use their Bonus Action in this way?

Forgive me if this question is obvious; tomorrow I’ll be running my very first game as a DM… or period (never played D&D… ever)

Just looking to brush up & cover all bases here

The Two Weapon fighting rule (as opposed to the fighting style of the same name), applies to every character.  So yes, every first level character gets a bonus action, if they meet the conditions of the rule (see below).  A character can only use a max of one bonus action per turn, so characters that have multiple options for bonus actions can only use one per turn.  

In terms of attacks, if a PC is using an eligible weapon (a light melee or thrown weapon) to take the attack action, yes, they can make a second attack  (roll) with the other hand, assuming that hand is also holding a light weapon.  That presumes they have two such light weapons (for example, daggers, shortswords, etc.). Note also that the damage for the bonus action does not get a ability score bonus like the main attack does.  (That's a feature of the Two-weapon fighting Fighting Style)

Does the Bonus Action attack receive a modifier?

Also, does a Two-Weapon Fighting Bonus Action still happen if the initial Action’s attack misses?

Does a PC still get to roll a second d20 for their Bonus Action if the initial Action fails?

Quote from eightyocho>>

• Does the Bonus Action attack receive a modifier?
• Also, does a Two-Weapon Fighting Bonus Action still happen if the initial Action’s attack misses?
• Does a PC still get to roll a second d20 for their Bonus Action if the initial Action fails?

Two-Weapon Fighting

When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative.

If either weapon has the thrown property, you can throw the weapon, instead of making a melee attack with it.

• The two-weapon fighting bonus action has two requirements:
1. You must be holding two light, one-handed melee weapons,* each in a separate hand.
2. You must have taken the Attack action and used at least one of those two weapons.
   
   Nowhere does it state anything about any of those attacks needing to hit.
• The two-weapon fighting bonus action states that the character’s ability modifier does not get added to the damage roll for the bonus action attack (unless it’s negative). Nowhere does it state anything about not adding that modifier to the attack roll.
• No, they don’t “roll their attacks twice” at all, that’s not what it states. I says you can make a single additional attack as a bonus action.
       As a 1st level Ranger you can make 1 attack using the Attack action. If you are using two eligible weapons,* you can then make a second attack using the other weapon as your bonus action.
       When you reach 5th level and gain the Extra Attack feature, you can make 2 attacks when you take the Attack action. If you are using two eligible weapons, and use either one for both of those attacks, then you can then make a third attack using the other weapon as your bonus action. if you instead use one of the weapons for one attack, and the other for the second attack, then you can use either one for the third attack you make as your bonus action two-weapon fighting attack.

*The current list of light, one-handed melee weapons: club, dagger, handaxe, light hammer, scimitar, shortsword, and sickle.

I hope that helps.

So say a 1st level Ranger has a shortsword in their right hand and a dagger in their left hand and a Dexterity of 16. Both weapons are light. They take the attack action and attack with the shortsword, rolls d20+5 (+3 Dexterity. +2 Proficiency Bonus) to hit.  Hit or miss, they can use their bonus action to attack with the dagger (again d20+5 to hit). If the shortsword hits they roll damage 1d6+3 (+3 Dex). If the dagger hits they roll damage 1d4. No bonus on damage from Dex. 

As IamSposta pointed out at 5th level they can attack twice with the shortsword as their attack action and once with the dagger. 
Actually their is no “off hand” in 5E so it could be reversed and use their attack action to attack with the dagger and bonus action to attack with the shortsword. Might be worth it if one weapon was magical and the other mundane. 

Also worth noting dndbeyond puts that two weapon fighting information on lots of character sheets, because it’s something everyone can do, assuming they have the right kinds of weapons. Characters don’t have to, and often, they have something better to do with their bonus action, but technically it’s an option.