What does it mean for a girl to send me "love you"

From your description, we can see that this girl has a crush on you. She sends you "love you", which means she likes having you in your heart. She is outgoing and simple. You don't speak first, only she speaks first. As for her intimate relationship with several boys in the class, it may be that you don't have to care that they are your own male girlfriends. If you also like her and secretly love her, you should cherish each other and get along well.