FreeBusy always looks at your calendar to determine your available times. If you are not available at certain time or on certain days, all you have to do is put busy calendar event or OOF (out of office) event.
Here is how to do it. For this example, we are showing Outlook calendar however you can do the same on any calendar that you use.
Step 1: Create a new event or appointment
Step 2: Give it the appropriate name.
Step 3: Mark event as Busy or OOF
When you put this event, FreeBusy will remove the times from your available times on your FreeBusy Booking Page.
This way you can block the calendar for holidays