Hello, this is a piece written by Dmitri Shostakovich as a part of his Jazz Suite. It's commonly known as Waltz No. 2 and is used in quite a few forms of media.
This piece was a composition Shostakovich was forced to write under the soviet regime as a form of propaganda music. However, the saxophone was illegal to be played in Russia at this point in time due to it's connection to the American (specifically African American) jazz scene.
Shostakovich specifically wrote in the famous saxophone solo for this piece in order to make it technically illegal for a Russian orchestra to play.
Sorry for the history lesson, but I really like this piece. I hope I did it justice, thanks for listening!