Brother from another mother.
a long way of saying "homie"
or something of the sort.
It sounds better though, because it rhymes and whatnot. Almost like a little poem or something.
It originates from some movie that I can't recall the name of.
Literally, one's half-brother who is a result of a different father, but the same biological mother. It may also be used figuratively as a simple figure of speech.