A muslima is a girl or woman who is the follower of religion Islam. A person who is male with the same religion is called Muslim. There are various names that are used in this regard so, when you meet a girl or woman it is not necessary that she introduces herself to you as muslima. She can say that she is a Muslim woman.
It is generally accepted that the one who want to be addressed as muslima actually desires to give the impression that she is a young girl mostly teenaged. It has another impression that she wants to show that she is an acute observer of the social scene.
This term can be explained with the help of a lot of examples, such as Latina etc. A lot of examples can be set forward similar to this. Latina is a woman who is the aborigine to that.
Well, let me clear it abundantly to you that muslima isn’t official or religious title for a woman who follows the religion, Islam. It is a matter of personal choice. If you want you can call yourself muslima otherwise you can simply be said to be a muslim girl.