Yes, you can block time for your specific staff member in case he/she isnt available
1. Go to Calendar >> Staff Calendar
2. Click on Add Block Time
Here you add block time for particular staff
3. Select a Date or it can be for current date as well
4. Select a Staff for whom you need to add block time
5. Select Time Duration, Start Time and End Time
6. Give a Reason to make them block
7. Click On Save
Blocked time will be added
Note : After adding a block time admin will not be able to book any appointment under that particular staff member.
Also, here is the video tutorial for your reference