A bugler is the person who plays the bugle, not the instrument itself. In the army, the bugler's job is to blow the calls that tell everyone what to do next. You can also find buglers in marching bands and at ceremonies. The word is just bugle plus -er, the same ending as in singer or teacher: the one who does it. Though actually, a line that calls this a musical instrument is describing the bugle. The bugler is the player.

號手；司號兵