It's the Italian female equivalent of the male adjective "
Bravo".
it is then referred to a woman to compliment and approve her action.
At the theater you should yell "
BRAVA!" to congratulate a
Soprano or other woman singer, not
bravo (that's for a man)!
Bravissima is the superlative for a woman, so you can yell that to. (Bravissimo for a man)