The Heading Block allows you to insert an HTML Heading into your page. By default, the heading will be a H2 but you can change this using the icons on the Heading Block toolbar or in the Settings Sidebar.
Once you've added your text to your block, there are further options available in the Settings Sidebar. You change the HTML level for the heading (i.e. H1…H6) and you can also add an HTML Anchor to the heading which enables you to create a link to a specific part of your page.