They look like bipedal domestic cats. They come in as many colors as your average domestic cat does.

Catfolk Traits

Darkvision

You have a cat's keen senses, especially in the dark. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

Feline Agility

Your reflexes and agility allow you to move with a burst of speed. When you move on your turn in combat, you can double your speed until the end of the turn. Once you use this trait, you can't use it again until you move 0 feet on one of your turns.

Cat's Claws

 Because of your claws, you have a climbing speed of 20 feet. In addition, your claws are natural weapons, which you can use to make unarmed strikes. If you hit with them, you deal slashing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.

Cat's Talent

You have proficiency in the Perception and Stealth skills.

Dietary Difficulties

Catfolk are carnivores: their digestive system is used to meat, but not to plant fibres.
Advantage to CON checks relating to raw meat.
Disadvantage to CON checks relating to fruits and vegetables (excluding juice).

Cat's got your tongues

You speak common, and one other language of your choice.

Preparedness

Catfolk who may get into scuffles with the law or who prefer not to use their real name usually have a few alternate identities on the backburner. They use an alternate name, accent, some cosmetic features and occupation among others. (Writing up this identity is the player's responsibility)

Ability score increase

Your Dexterity score increases by 2, and your Charisma score increases by 1.

Age

Catfolk have lifespans equivalent to humans.

Size

Catfolk are taller on average than humans and relatively slender. Your size is Medium.