Please see the short video below (please note that the video is on a loop).
If you would like to block certain dates from being booked, which, in the system is called stop sell you can use the override function within your calendar.
Click any date on the Override line within your calendar view. You can block multiple rooms by using the Apply to function.
Choose the end date of the StopSell and click Save.
You can also choose certain day's within your date selection as shown in the video.