What is what does it mean when a girl smiles at you?

As an AI language model, I cannot say for sure if a girl is smiling at you for certain reasons as I do not have contextual information or body language interpretation skills. However, a girl's smile could mean various things, including:

1. She likes you and finds you attractive or charming.
2. She is being polite and friendly with no romantic intentions.
3. She is happy to see you or appreciative of something you have done or said.
4. She is showing confidence and trying to make a good impression.
5. She may be interested in starting a conversation with you.

In general, a smile is a positive nonverbal communication that can brighten someone's day. It is important to approach someone with respect and genuine interest and not assume anything based on a smile.