WooCommerce is an eCommerce plugin for WordPress that provides flexibility and customization options to online retailers, outmatching other platforms like Shopify when used effectively. Installing WooCommerce requires a WordPress site, which can be set up with a hosting provider, followed by installing the plugin, setting up store details, and customizing the theme. Customization options include editing the theme, adding plugins, and managing product listings, orders, and customers. With its vast array of features and customization options, WooCommerce enables users to build unique eCommerce sites that cater to their specific needs.