Answer:
she does that to feel the music by her feet
It could be helpful because the art tends to look more pleasing to the viewer when the artist uses 3 or less primary colors.
Just ask your questions on here but put "PLEASE HELP! WILL GIVE BRAINLIEST!!" or something like that at the beginning of it. Usually draws people's attention towards it. Also, if the question is worth a lot of points, I would also recommend putting that too.
Because if you are alike its easier to have ideas with eachother :)