Brandy -- Boxing with Angela Simmons ... Check Out This Hook

Brandy's still dishin' out the hits -- only this time, it's in a boxing ring ... 'cause the singer's working on getting her Mayweather on with her good friend Angela Simmons.

Brandy and Rev. Run's daughter strapped on the leather and worked out at Supreme Team Boxing in NYC -- where they've been doing some hardcore pugilist training for a while.

Coach Nelson at the training center tells us the ladies have some real talent -- "If they're really serious about it, they could compete at the amateur level. Especially Angela."