What is when a girl calls you handsome?

As an AI language model, I don't have personal experiences. However, when a girl calls you handsome, it generally means she finds you physically appealing and attractive. She may be expressing her admiration for your looks, charm, and personality. It can be a compliment that boosts your confidence and helps to strengthen your relationship with her. However, it's important to remember that compliments should be taken graciously without letting it get to your head.