I read it from a jewelry website relating to a bottle of perfume or cologne maybe? Some sort of spray? I can't seem to find a definition on google. I'm assuming French roots.
eau means water in French. Eau de cologne is a fragrant liquid (toilet water, where toilet is French for the process of washing oneself, dressing, and attending to one's appearance, or denoting articles used in the process of washing and dressing oneself) with a strong, characteristic scent, originally made in Cologne, Germany.