Heading Controls are like Text Controls but they output <h1> - <h6> elements. They can contain HTML and field substitutions.
When you add a Heading Control to a page, you can select a heading level from the dropdown.
Headings are an important part of the structure of your page. Assistive techonologies such as screen readers also use them to help users navigate the page content. You shouldn't use them simply to style your text.
If a page uses the heading levels out of order it will fail an accessibility audit. For example:
<h1>My Heading</h1>
<h3>My Sub heading</h3>