If a female refers to you as "bro," it suggests she feels at ease with you. She wants to chat to you and tell you about her troubles since she believes you can assist her. She needs a shoulder to weep on and doesn't have a partner, so The Bro is the best option she has to vent to. A female calling you "brother" shows that she holds you in high regard. She would never call someone else's brother without any reason. It could be your sister or mother, but only if they are not alive. Thus, when a female calls you "brother," it is because she values you and your relationship with them. Even though she may be alone, she isn't lonely because she has her family around her. If a female calls you "Bhaiya" or "bhai", then it means that you have impressed her very much. You have done something worthy of respect and she would like to show this to you by calling you by your pet name. This is usually done by sisters towards brothers or mothers towards sons. Calling you "baa" or "baba" means that you have saddened/frightened the female. Perhaps you have done something wrong and she would like to warn you against it. Or maybe she is unable to speak up herself and so she makes another animal sound to let you know how she feels.