How to know if a girl likes you?

well ,this girl I never talk to before aproach me, she was like lets get to know each other better , but she hang in a totally diff group , so we dont know each other, we talk where we work ,life,and near the end she asked if I had a gf I say no she say me either (happily) then told me her freind did.
oh yeh she sit far away but sat like a seat next to me with her friends during a movie in class and then 5 mins later she aproached me.

Sounds like she may like you. If you're interested in her then get to know her better. Don't be afraid to go up to her either!

Know her better and maybe something will change