The noun "mute" means "someone who cannot speak." Some people are born unable to make sounds, and some people who have experienced trauma lose the ability to speak.
When "mute" is a verb, it means "to turn the sound off" or "to change something so it makes less sound." If you mute a movie, that means the movie is still playing but the volume is at zero. If your neighbors are noisy, you might close a window to mute the noise.