WooCommerce is a free eCommerce toolkit for WordPress.
In a Modellic theme it is used as a base for models (but it can be a products or anything else). WooCommerce allow you to create posts (of product post type) which you can be used for any purpose, add any numbers of attributes, categories, tags easily and without any coding. Thanks to that you can group and filter your items allowing user to find a perfect match.
You can use it as a eCommerce platform, catalog, or as a booking platform with WooCommerce Bookings plugin supported by the theme.