The power rating of an appliance is a measure of the energy transferred per unit time
The power rating for domestic electrical appliances is normally given on a label. This will include:
The potential difference required to make the device work (eg. 230 V in the UK)
The frequency of the supply (eg. 50 Hz in the UK)
The power rating in watts (this varies for each device)
The higher the power rating, the more energy is transferred per second