I see that according to Google Translate, "song" and "music" both translate into <em>música</em> in Portuguese. That is surprising to an English speaker.

"Song" is produced by the human voice.

"Music" usually refers to something produced by musical instruments, like a piano, or a guitar, or a jazz band. It does not have words.

In English, "song" can be an uncountable noun for the art of singing. It can also be a countable noun, "a song." "The Girl from Ipanema" ("Garota de Ipanema") is a song.

"Music" is never a countable noun. There is no such thing as "a music." We need to say "a piece of music" or "a musical composition." Beethoven's Fifth Symphony is "a piece of music."

A person who performs music is "a musician."

In a song, words are sung to "a tune." Each syllable falls on a musical note. A song has both "words and music." The words may be called "the lyrics" (or simply "the words.") The pattern of tones is "the music." "The Girl from Ipanema" has music by Antônio Carlos Jobim and lyrics by Vinicius de Moraes.

There is an ambiguity about whether or not the word "music" includes "song." Sometimes it does, sometimes it doesn't. There is a kind of theatre work that is like a "play," but it includes many songs, and the songs tell part of the story; it is called "a musical comedy" or "a musical." However, a singer is never called "a musician."

HI Daiane!

"We can sing a song." [lyrical/ combination of melody and words]

"We can listen to a music." [with musical instrument, combination of lyrical songs and musical instruments]

Have a great day!

Well, technically speaking, a song is something that we sing. “Music” is a more general term, and may refer to instrumental melodies, tunes, etc.