Well it sort of depends, it's up to the girl.
Some girls just want to dance with anybody and want to be out there the entire time and they're the ones that will simply grab a guys hand and pull him onto the dance floor. those are usually the confident flirty girls that are real outgoing. (or drunk)
Then there's the other girls that are way too shy to ask any guy to dance, and wait closeby the guy they like to wait and see if he'll ask them to dance. This ends up being most girls because secretly all girls are afraid of rejection, even from a guy they know would love to dance with them.
hope i helped!