OC (original character) means that you make up your own character. It can be any character you want it to be and you can use the character for your rp. Like for example you do something like this :

Name
Age
Looks
Personality
Backstory
Likes
Dislikes

Something like that is what you could use for your character so you'll already know how your character will be. It can also be any type of character you want. For example there's things like tsundere, yandere, shy, sweet, any type Of character you want to make then go for it.

You can even choose what you want the character to look like.