Girl playing footsie with me, what does this mean?

Your age is a major factor. Middle school or high school? She must like you - no matter the reason. if you are freaked out about it, stay away from her. If you do not consider yourself to be gay/bi, do not reciprocate the 'playing footsie' as you are saying you're into it. If you think you might be, you can always talk to her privately and ask her questions.