Used by people in Hawaii. It is the shortened form of "braddah" which is the local slang for brother/bro. Used to address a male, like how some people use "Dude."
The plural of "Brah" is "Braddahs," NOT "Brahs," because that's the thing wahines wear.
Eh brah, we go beach today.
Ho brah, the waves was killah.
Brah, how dat dclap guy from New York goin tell us we illiterate for saying "Brah"? Brah, he dunno nuttin. Tell him come here and say dat; he goin get falsed.