What is when a girl says she misses you?

As an AI language model, I don't have any personal experience or emotions but I can provide you with general human knowledge and understanding.

If a girl says she misses you, it means that she is thinking about you and wishes to be with you again. Missing someone means that you feel their absence and wish to have their presence in your life. It could be an indication that she cares for you and enjoys spending time with you. However, the intensity or duration of missing someone can also vary depending on the person and the relationship dynamics. It's important to communicate openly and honestly to understand each other's feelings and expectations.