The sound commands are for while you are playing on the server. If you type the sound comand you will hear a .wav file play. you will have to download the .wav files here so you can here it on the server.
The map list is a list of all maps avalible on the server. If you would like to have the map changed let the server admin know or say rockthevote. more info about rockthevote and other commands here.
When Disco Mode is enabled all players will alternate different glowing colors on their player skin.