Chinese don't know how to "carve" meat, they hack it into bits with a cleaver. The aprons are to protect their clothes from the splattering. The "slop" on the table next to the cutting board is hard to see in the photo. It is either the meat they have finished chopping, pushed to the side to make way on the board, or refuse bits left over (never actually seen this 100% is served usually even here at home for my fam) from the chopping process.