Resource vacations are a way to tell checkin24-7 when a resource is available for reservations. The only difference is that checkin24-7 uses an opposite approach -- instead of saying when the resources are available, checkin24-7 assumes they always are and you need to specify vacations, that is, periods of unavailability.
They are one-time or
recurring periods when a resource may not be reserved (e.g. because of
reparations/renovation, because of public holidays or because the owners go on vacation). You can
enter vacations (one-time, or recurring weekly, monthly or yearly) in site
settings / resource vacations.
Please note that administrators can still reserve during vacations. They will be, however, presented with a warning message and the reservation will be marked as conflicted. Of course normal users cannot reserve during vacations.
If you enter vacations for a period with existing reservations, you will see the list of reservations plus you will need to confirm if you still want to add the vacation, in which case all existing reservations affected will be marked as conflicted.
See more about conflicts here.
If you'd like to often make manual updates to the availability for specific dates, you should go to
Availability in the Schedule&Reports tab. This will let you check and set availability on a calendar for any given day of the year.
If you need a more flexible way of determining availability (e.g. specifically for given customer), you can see
the unavailability message section in Q181.