A blue watch can be translated as "a blue watch" in Engpsh. It is simply a way to describe the color and type of watch that you are talking about. The word "watch" in Engpsh can be used to refer to any type of timepiece, whether it is a wristwatch, pocket watch, or other type of time-keeping device. The word "blue" is used to describe the color of the watch. So, if you wanted to describe a blue watch in Engpsh, you could simply say "a blue watch."