It simply starts growing back. Kinda like planting seeds. If it takes your hair a month to grow a quarter inch, then the bald areas should have a bunch of quarter inch long hair after a month.
It’s as if a folicle that is dead is suddenly alive again and just starts pushing out hair like all the others do.
It is actually even better for women in my opinion for the simple reason that a guy with hair loss looks normal. Women with especially thin hair kinda stand out. It doesn’t work any better for women, but it’s impact can be more emotionally rewarding for them.