The Website Builder application available for Odoo 11 is commonly known as a CMS (or content management system). A CMS is a collection of tools that allows you to structure, organize, and manipulate your website without having to interact directly with the inner workings of your website. A key feature of a CMS is the ability for nonprogrammers and those with little technical expertise to create and edit content on the website once the initial structure of the site has been designed.
In many ways, Odoo is coming into a very crowded market that has a great variety of both open source and paid CMSs that you can choose to build your website with. Here are a few popular website CMSs, all of which, at this point, have considerably more configuration options and significantly more installs than Odoo.