A more thorough explanation:

Broadcast Music, Inc. (BMI) is a performing-rights society in the United States that licenses the public performance of musical works on behalf of copyright owners.

For example, if a restaurant wants to play music for its customers, they need to obtain a license from BMI to legally play the music. The license fees paid by the restaurant are then distributed to the copyright owners of the music.

BMI represents over 17 million musical works from more than 1 million copyright owners, including songwriters, composers, and music publishers. They provide a valuable service to both music creators and businesses that want to use their music.