Heading 1 or h1 is the text of the first outline heading of your page.
It's the default value for the title and can be used as variable.
For instance:
The ''h1'' for this page is: ''$h1''
The h1 for this page is: Page Heading 1 (h1)
By default, the heading 1 is the first outline heading of your page but you can change it via the metadata manager.