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...
In meteorology low is the cold air low pressure system that often brings more bad weather do to the lower barometric pressure.
from the info you gave me i think its Flo Rida
"Low", the single by Flo Rida from his recent record, Mail on Sunday