This is not the complete version of the William Tell Overture, but it is one of the most famous sections! The Finale, also known as the March of the Swiss Soldiers, is a very famous piece of music. William Tell is an opera written by the Italian composer Gioachino Rossini which premiered in 1829.
This section of the overture has been used in many many places, such as in Looney Tunes and Disney cartoons, most famously as the theme music for The Lone Ranger.