You may want to create a product category that contains a list of the main categories or a list of products under a particular category. In that case, just manually create a product category. 

In JMango360 Back Office, navigate to the Design module > Add Feature > Product Catalog.

Now you can:

1. Edit the page such as changing the page title, adding menu icon, etc.
   
2. Associate the category with a desired page.
   

1. Add thumbnail images to the sub-categories under the category (if any) and specify the layout for the category.