You can either define separate resources for e.g. separate hotel rooms (this is good if you want the users to be able to select a specific room) or you can specify a quantity greater than one of any resource. In such case you can also assign names to specific units (such as room numbers or yacht names). This can be done in resource settings ('unit names' button). If you decide to assign unit names, you will be also able (as the administrator) to assign specific reservations to a given unit. This way you can use the system for detailed management / logging of rentals.