My mom won't let me use our xbox live because she knows people can use dirty language, even though I've been telling her that you can mute or hide it... what should I tell her?:confused::(

Her house ,her computer,her rules.
The only thing you can do is take her to the site and show her.

You can't blame your mum from wanting to protect you from the things that are said over live,and yes you can mute them, but you will still hear them the first time, they say anything and your mum is trying to stop you from hearing those kinds of things,

And as art lady says her house her rules, and to be honest if you show her that you can mute those kind of people its still going to reinforce her stance that such language is spoken there and hence she won't want you there.

You problem is simple to fix: Just show your mom that everyone is okay by muting everyone! After awhile, she will loosen this grip and you can start unmuting some people.
Don't screw it up though, for this is a long ,but positve to work, process. :))

Young kids should not be on services like this anyway. I used to play on X Live and its full of 12 and 13 year olds, they give out their addresses and stuff like that to people online.

I had to block Habbo Hotel off my router when I was younger and lived @ home because my teenage brother had people calling him from all over the world