Calendar synchronization helps you to reduce the chances of overbooking significantly by connecting the calendars between OTAs (Airbnb, Booking.com, Vrbo) and GoDirect.
In the example you can see three imaginary calendars of the Cozy Cabin.
The calendars are not connected to each other in any way yet and that's what causes overbookings.
This is where the iCal calendar connection can help.