It's a word meaning "okay then". It's a mix of the words "yo"
and "k" meaning "okay" for short. This meaning is used to say something stupid, that you have IM or said.
Person A: hey man what's up?
Person B: wasted, just like always
Person A: yo/k?
Person B: what's that mean?
Person A: search it up in Urban Dictionary
yo bra is something that people hear is ONIONS mispronounces the greeting: "yo bro".
WILLIAM: YO BRO!!!!!!!!!!!!!!!!!!!!
KEVIN: did you just call me a BRA?????????? did you just say YO BRA to me?????!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!