What a custom voice is
A custom voice is a reusable voice profile built from a recording of you singing. Once it exists, you can choose it when you generate a Suno V6 song, so the vocals follow your voice instead of a generic one. You write or paste the lyrics, pick the style, and the song is sung in your voice.
The voice belongs to your account. It shows up in your own voice list on this page and in the persona picker of the generator, and it is not published anywhere.