A form of city slang, often used in the hood (ghetto neighborhood). It's just like any other language, you have to know how to speak it in order to understand it. Often people who understand ebonics, also understand the proper use of words. Just because they can understand ebonics, does not mean that they are unable to speak "properly".
Ebonics: "I done ate my grub, now I best be gettin' on"
Proper English: "I've eaten my food, so now I should leave"
Ebonics: "I finna kick it with mah homies up in mah crib"
Proper English" "I'm going to relax with my friends at my house"