The numbers represent the current level of the girl. To level up a girl you will need to film them using the Film studios. There are 6 studios to film your girls, 3 that can be unlocked with cash and 3 studios that can be unlocked with diamonds.

The level of each girl is determined by the sum of the levels of all poses a girl can film. There are a maximum of 14 poses a girl can have with only a couple of the girls having the possibility to film in all available poses. For example, Indira can film in all available poses.

By leveling up your girls you unlock additional sex positions for them and also increase your stamina for the BJ Challenge mode.