In your admin section:
Go to Availability -> Hours -> Online Reservation Hours
Toggle "on" or "off" each individual day to reflect if your restaurant's availability
Adjust your "Hours" each day with the drop-down icon to reflect start and end of service

To add a block in service:
Select the "+" icon
Adjust hours as needed. Select "Save" button each time to save changes.

You can also block specific slots. To do so:
Select the filter icon

Select and/or unselect any slot as you want to make them available
