A housekeeper is someone whose job involves cleaning other people's houses. In some cases, a housekeeper also cooks meals for her employers.
It was once common in many countries for wealthy families to employ a live-in housekeeper, who may have been called a maid or a servant. Today it's less typical, although some families hire workers to clean occasionally — these people might come once a week and are usually called <>housecleaners rather than housekeepers. The word uses the sense of keep that means "maintain or preserve order."