The Medieval Realms plugin supports a variety of chat console commands. Here is an exhaustive list, in order of priority.

/pnb
Launch the planks and beams texture plugin

/sos
Save our Souls! This command will fast travel both you and your mount to the servers spawn area. This can be used at any time in PvE mode, but in PvP mode you will need to have full health

/help
This will start a conversation with the bot

/w
Whisper