Well done! You've found the french horn!
The French Horn belongs to the family of brass instruments. It is easy to recognise with its tubing, roughly 12 feet long, wrapped into a coil with a flared bell.
Sound is created through vibrations as the player is blowing air through a cup shaped mouthpiece into the tubes of the instrument. To make different sounds, the player adjusts the opening between their lips, by pressing the valves and by moving the inside of the bell.