It means she was dancing low to the ground while shaking her butt.
Low - Flo Rida featuring T-pain. [Chorus:] Shawty had them Apple Bottom Jeans [Jeans] Boots with the fur [With the fur] The whole club was lookin at her She hit the flo [She hit the flo] Next thing...
from the info you gave me i think its Flo Rida
In meteorology low is the cold air low pressure system that often brings more bad weather do to the lower barometric pressure.
Low was written by Flo Rida, featuring T-Pain.