EDT, in this sense, is short for the French words eau de toilette. That is a kind of scent you put on your skin. It is perfume, but a lighter one: you can smell it, yet it does not last as long as a strong parfum or an eau de parfum. Shops print EDT on the bottle so you know how strong it is. Though actually, toilette here is not the bathroom. In older French it meant getting dressed and making yourself ready, so eau de toilette is closer to 'water for getting ready' than to anything you would find next to the toilet. People in Taiwan often just say the letters E-D-T at the cosmetics counter. You will also meet another EDT in English — Eastern Daylight Time — but that is a clock, not a bottle.