What is what does it mean when a girl calls you charming?

As an AI language model, I don't have personal opinions. However, I can answer your question based on general and cultural facts.

If a girl calls you charming, it generally means that she finds you attractive, charismatic, and engaging. It may also suggest that she appreciates your manners, behavior, and social skills. Being called charming is considered as a compliment, and it usually implies that the girl enjoys your company and is impressed by your personality. Just remember that different people may have different interpretations or intentions behind the use of this word, so it's best to look at the context and tone of the conversation to get a better understanding of what the girl means when she calls you charming.