it's usually a way of saying that she needs some space and wants to focus on her own needs for a while and worry about being in a relationship some other time.
It means one of 2 things rather she needs time to her self deciding what she wants in/with life or she doesnt know how to dumb you so she told you that.
SHE MEANS...she needs help
It means he needs to talk to her
Probably that she thinks you fancy her.
shes doesn't really like you
It probably means that she is enjoying the time that she has to herself.
it means that she trusts you allot
it means that she is not happy with him and they both don't have proper understanding.
It COULD mean that a girl needs to get some sexual activity from a boy.
they mean that you don't have "faith" in yourself, that you don't think that you can do certain things, not brave enough to try
It means thank you for the offer.
Sounds like she needs to think about it. Don't worry about it, she hasn't said no yet.