FREE means that the room is available and can be reserved or booked.

RESERVED means that one or more prospective clients have sent reservation requests for the same room and dates BUT so far none of them has made a deposit payment.

Incoming reservation requests for the same room and dates are placed into a reservations que in the order they arrive. Reservations made earlier has precedence over reservations made later.

Beware that a reservation only protects against later reservations BUT NOT against a firm booking. Even if you have a reservation, until you make the deposit payment, the room will continue to be available for anyone who is willing to make a firm booking.

BOOKED means that a deposit payment has already been made for the specified room and dates and that the room  is no longer available. A firm booking cancels all existing reservations even if these were made before.