It's availability for 210 days and actually let for 105. The letting is at commercial rates, so freebies for the family or own use don't count. They can put someone in for up to 155 days in the winter.
It's not cheap to run a holiday let - laundry, trying to find cleaners, advertising and booking fees, rubbish collection, non-stop repairs and renovation, and for the sake of your sanity, a management agent. That bijou residence in a beautiful location can easily turn into a money pit if foreign holidays are cheap.