Both Pages and Posts are used for displaying your site's content. Pages have several different templates that you can choose from which determine how its content is displayed and even what content is displayed. In addition, each page can have its own in-page menu and its own sidebar. Pages can be hierarchical and if a page has a parent, breadcrumbs will display at the top of it if this feature is enabled.
To create a page, you can either hover over + New on the top menu and click on Page or you can click on Pages in your dashboard and click Add New.