To Serve is defined as to be a servant, to place food before; to wait on, and to be of assistance to.
Service is defined as the occupation or duties of a servant, the act or means of serving, and the duties performed as an occupation.
Serving your Empress is simply, the act of making her life easier. It is complying with all of her wishes, order, and desires. This includes, but not limited to offering to clean her home, to wash her laundry, cook for her. Offer your Empress a massage, to be her chauffeur, etc.
Domestic Slave Training:
You're lucky to have such a strict, sadistic, yet patient disciplinarian for an Empress. You'll be a proper slave no time yet!
Experienced slaves who think of themselves to be worthy to serve, with only light training.