This is a Default Layout. By default, this layout is being selected in each page and post. Unlike other layouts, these layout can be changed globally. So, that you can change all your page or posts layouts by changing from Customizer – Theme Options – Layout Options – Default Layout.
In this example, Right Sidebar (Content – Primary Sidebar) is being choosed from Customizer – Theme Options – Layout Options – Default Layout. And this page’s layout is being set to Default (in Layout options). So, this page will also have a Default Layout (i.e. Right Sidebar).