Actually, the song consists of three parts: introduction - 30 seconds of silence, the majority - 2 minutes 23 seconds of silence and the conclusion - 40 seconds, even more silence.
John Cage is known as an avant-garde composer and artist. His work in the 1940-50-ies are strongly influenced by Zen Buddhism. According to the authors, "4, 33" makes the audience listen to the sounds of the environment and, thus, to come into harmony with it.
The song "4, 33" can be performed on any instrument. Here is an example of its performance on the piano.