It allows for other mods to add chat commands in a neat way without them clashing with each other.
This mod by itself only has a help command, you'll need to get other mods, such as GameMaster, RightToBearArms, or Overseer to get more fun/useful commands.
If you'd like to give other players permission to use commands, you'll need to use the PermissionGroups mod.
That can be configured to anything you want in the "BepInEx/config/lammas123.ChatCommands.cfg" config file, however the command prefix is determined by the lobby owner, so you won't be able to use your custom prefix if you're not the host.