All products that have the product option Bookings / Reservations assigned will display these links when displaying all listings.
Or you can access the bookings system from within a product / listing
The display will depend on the grid settings set in the setup. There are 2 examples of adding a booking using small time slots or days. Click a free green slot + to add a booking a count of available free slots will be displayed.
If free slot clicked we have a dialog box open where we can enter the new booking details