The calendar button can be useful in situations when you need to look up availability on a specific date in the future or even searching for a reservation or block in the past. This is an easier option than scrolling or changing the amount of days shown in settings.
Above the calendar on the right hand side, situated to the left of the "New Reservation" button, is the "Select Specific Date" button. This button allows users to jump to a specific date rather than the present one.
When you click the button, a dropdown calendar will appear so you can easily select a date by month.