What does it mean when a girl stares at you?

I get this question quite a lot when they stare at me for 3-5 seconds. Besides this they also bite their lip, slightly tilt their head upwards whilst looking, their eyes (in general) go bigger and they look at you from the corner of their eyes whilst facing in another direction. I'm not sure, go ahead call me whatever for not knowing, I guess I missed out on this. Could anyone help please to define each of the following. Thanks!!