to make a sound or device able to be heard again after it has been muted (= made unable to be heard)

I couldn't see how to unmute the TV without using the remote. 不用遥控器，我不知道如何取消电视静音。

to make a person able to be heard, for example when using video conferencing software

Participants will be able to unmute themselves if they need to contribute to the discussion. 如果与会者需要参与讨论，他们将能自己取消静音。

to allow someone's messages, pictures, etc. to appear on a social media website when you look at it, after a time when they have been stopped

Click the "X" next to the name of the person you want to unmute. 点击你想取消隐藏的人的名字旁边的“X”。