She's buying into a new set of possibilities, even when the target is just a punching bag, not yet an opponent. It's a transformation for her to be overtly aggressive. And to have that aggression accepted. It escalates if she puts them on to spar, not just to drill. It's another transformation to take a solid shot to the face and not turn away or burst into tears.
Many women never make it that far, of course.
But a few make a choice that lets them discover many things they never knew about themselves. They rise to the challenge of sparring, as a workout and learning experience with instant payback for not being alert, for not being fast enough. It's the challenge of being first to get your fist in the other's face. To anticipate the other's moves. To have the strength and quickness to keep going round after round against someone trying to do the same to you.