The WooCommerce Nested Category Layout gpl extension allows you to show products organized by category and sub-category on the shop and catalog pages. By breaking products up by subcategory, this plugin provides an intuitive and attractive catalog layout that your customers will appreciate. Here are before and after shots of the shop page using Nested Category Layout.
WooCommerce typically allows you to show subcategories on shop and category pages (or subcategories and products, but this can look messy). While this is a handy option, it requires that customers click on categories, then subcategories to simply browse products and looks like this.