After successfully enabling subcategories you can see them listed in a Grid view on the frontend. You can select the number of columns depending upon that the frontend will review the Grid view. To select the columns Navigate to Catalog > Categories and then select the category. Scroll down to Sub-Categories Settings. Here you will have the option to upload the thumbnail image, short description and number of columns. Please refer to the image below. Each of the subcategories will be listed with a description, background and image as defined by you.