FLOOR REGISTERS

[MYCAMH]

I'm a first time MH owner & wanted to know what the registers in the floor are for. I feel cool air coming from them & the heat/cool registers are in the ceiling. There also is a cold air return screen in the laundry room wall @ the furnace compartment. I want to put new wood flooring in & was thinking of covering them over. Please help before I do something I shouldn't.