i dont no "
The first sign to if she likes you is if she stares at you alot (obviously she is checking you out). The second way to tell is if she comes up to you and makes an excuse to talk to you (she wants you to get to know her). The third way to tell is if she siles at you alot (she wants to tell you that she is a nice person). The fourth way isn't always correct, but she might tell her friends that she likes you (Sometimes it's just a dare or a rumor).
It means she is checking you out. If she is standing behind you and you feel her looking, she probably fanices you and just wants to be around you and look at you without being too obvious. if you fancy her back, ask her out.