The Product Categories section in your business account is used for classifying your products, and you should define your product categories before uploading your products or services. The way you define your products will help customers find your products/services when they do a search for an item in the future.
To set up the categories you'll be using, in your Account, under Retail Management, find My Categories
To Add or Edit a Category:
(As an example, let's say you are selling pants. Pants would be the main category).
To Add/Edit Sub-categories of a main Category:
(With our example above, there are many different subcategories of pants - jeans, khakis, chinos, leggins, sweatpants, etc).