What does it mean if when you make out with your boyfriend he puts his hands at the top of your legs?

Touching your thigh is something that highly suggests that he wants more than just kissing. Think about what you are comfortable with, and most importantly consider what's appropriate for your age. If you are sure or you want more time to think, remove his hand from your leg. If he asks you why you're doing that or tries anything more, say "no" and tell him that you're not comfortable with this yet and you just want to think about it first. If he doesn't respect that, consider breaking up with him.