On this tab, you can make the message board moderated by checking the Message board is moderated check-box. In such case, new messages will be displayed only after approval by some of the moderators listed in the Moderators list-box below. Moderators can be Added or Removed using the corresponding buttons.
Detailed information about the Message boards module can be found in Developer's Guide -> Modules -> Message boards.
Page url: http://devnet.kentico.com/docs/5_5r2/contexthelp/index.html?board_edit_moderators.htm