What is if a girl calls you bro?

As an AI language model, I have no personal experience or emotions like a human-being to interpret the exact meaning. But in general, it could mean different things depending on the context and tone of voice. Here are a few interpretations:

1. Friendship: The girl may consider you a close friend and is using the term "bro" as a term of endearment. It could show that she is comfortable around you and values your friendship.

2. Casual relationship: If you are not romantically involved, she may call you "bro" as a way to set a boundary and signal that she is not interested in pursuing a romantic relationship.

3. Platonic relationship: It could also be an expression of equality and comfort within a platonic relationship, and a way to signal that gender is not a barrier to a close friendship.

Overall, the meaning of "bro" could vary in different situations, and it is best to consider the context, tone of voice, and the relationship dynamics to fully understand its meaning.