The Boards plug in appears on the Prices part and particularly below the standard prices table where you can associate a price to each typology/occupancy.
It can be useful for you in case of a property with a restaurant, to manage the boards or rather the half board or the full board.
After load up the boards prices (bed and breakfast, half board etc.) on the dedicated section, you can associate a board during a new reservation creation and specify the relevant association with a full board, half board or bed & breakfast.
This will ensure Zak to record the board price multiplying it for the guests' number and the duration of stay.