A bugle is a simple brass instrument, similar to a trumpet but with no valves. Because it is unvalved, the bugle can only play a limited range of notes and is thus not suitable for use in orchestras, though it is common in brass bands and military bands.
Instruments similar to the bugle have been in existence since ancient times. The 'trumpets' used by Gideon's army in the book of Judges were probably closer to bugles than modern trumpets.
Bugles are often used to play loud fanfares, announcing the arrival of an important guest. In former times, messengers often used bugles to herald their presence, which is presumably why 'bugle' is a common name for newspapers (e.g. "The Daily Bugle").