Being muted in Counter-Strike: Source or Counter-Strike: Global Offensive means for a player or more/all players to be unable to communicate via chat (in-game) and/or via voice chat (in-game) or microphone.
Generally, players never get muted unless they are using excessivly offensive language via any of these communication channels. This can be temporary or eventually permanently (extremely rare though). While you can still type and/or speak, it won't be registred through the console, thus resulting in nobody seeing/hearing what you want to say.
On the wiki
Muting almost never happens on this wiki. If ever, banning would even be more common. Muting on the wiki will only be used whenever we want no one to be able to edit on the wiki for a certain period of time (usually a short time). This means that editing will be unable for both the pages and the talk pages. It can also happen whenever we want a particular user not to talk on the talk pages because he/she was "trolling".