If you're seeing this error, it's because your property does not have a kitchen defined in its details, and Booking.com deems it necessary.
There are two possible issues at hand, and different solutions to those:
Larger properties
If your property contains one or more rooms, it will be defined as one of the following by Booking.com:
Apartment
Aparthotel
Condo
If your property is defined as any of these in the Booking.com listing, then it must contain a kitchen or kitchenette in order for it to be published on Booking.com.
If the property details don't already contain a kitchen, you will need to add one on Hospitable.
To add a kitchen to your property details, go to:
Hospitable
Properties
Select your property
Go to Details on the left-hand side panel
At the top of the page, select Amenities
Click Add amenity
Under Kitchen and Dining, add either Kitchen or Kitchenette
Press "Done"
Once that is done, you can attempt to publish your Booking.com listing again.
If that still doesn't work, then please try giving it 5-10 minutes before trying again.
If that is still not working, or if your property already has a kitchen defined, then please contact support for further assistance.
A studio without a kitchen
If your Airbnb listing is a studio without a kitchen or kitchenette and you create a Booking.com listing through Hospitable, if you receive an error when creating the listing, please reach out to support. Note, Booking.com does not require studios to have a kitchen or kitchenette.