Upsell categories help organize certain types of upsells so that guests can easily view and consume what you have to offer.
Go to Property Management> Unit Groups
Click into one of the unit groups (adding a category to one group will be applied to all groups)
Navigate to the Upsell section and select Upsell Category List
Select Add Upsell Category
Name the Category and select Save
For details on how to create upsells, please visit this article