This is the Page called ‘Homepage’. It is designated as your site’s front page, as you can see if you go to Settings -> Reading. Keeping it at this setting is REQUIRED.
Any content (images, html, shortcodes, whatever.) entered here can show up as a section on the homepage. By default it’s not showing there. To show this text/content on the homepage, go to Theme Options -> Homepage Sections. Make one of the sections be set to ‘Homepage content text’.
Pro tip: You can create advanced content (like text columns, slick buttons, content with video backgrounds, and pretty much anything you can imagine) by using the included Visual Composer plugin. See the Plugins section of the documentation for more info.