I need help, why would a girl become very friendly with me eventhough she doesn't know me very well?

She started off giving me a shy smile and wave at me one day. Then she started giving me a big smile and wave and looking happy/excited to see me the next time. She was even giving me this big wave and smile from across the cafe. Next thing she is talking to me and now we are just talking naturally. I really like talking to her and she is asking me questions like where I grew up etc.

Is she just been friendly? Or does she like me? I'm just stuck not knowing. But I like her quite a bit.
I need help, why would a girl become very friendly with me eventhough she doesn't know me very well?
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