Sentence examples for a song from inspiring English sources

"a song" is a correct and usable phrase in written English.
It can be used as a noun phrase to refer to a specific piece of music or as part of a longer sentence to describe a specific action or idea related to singing. Example: "She sang a song that brought tears to everyone's eyes." In this sentence, "a song" is used to refer to the specific piece of music that the woman sang.