What is the minimum age for a girl to get her driving license?

The same as the minimum age for a boy.

The actual age depends on the country you are in (which you don't specify), and what type of vehicle you want to drive.

In most of Europe the minimum age to drive a car is 18, in Britain it is 17.

The age for a motorbike or moped is usually younger, and for a commercial vehicle (lorry) or bus it is older.