Hello.
1) In Booking Calendar Free version possible to block specific dates only by making “blank” bookings.
You can create “blank booking” at the admin panel at Booking > Add booking page.
2) The ability to block specific days (not times) based on seasons, possible in the Booking Calendar Business Medium or higher versions. Please read more about this here: http://wpbookingcalendar.com/overview/#availability
You can test Booking Calendar live demos at this page http://wpbookingcalendar.com/demo/ to be sure in functionality and do not have misunderstanding.
Kind Regards.
