When thinking of boas, you might imagine some giant snake that could rap your whole body and swallow you completely. That is the literal animal, the rap slang “Boa” is different and much milder.
Boa is an urbanized and corrupted version of “boy.” It was made very popular in Kansas. Originating from the African American youths, it is an expression of agreement or seriousness, if not used in its original sense.
“Boa! How have you been! I haven’t seen you since last year.”
“You better not be kidding when you told me about your PS5! Boa, that is legit!”