Header is a Section header and can be placed into a cell you have created. Headers are many times used in combination with a Paragraph and together they form a Section.
The Section element is described before and can be used to create the combination of a header and a Paragraph.
A header can be used alone. It is advised to create a grid on the page and a cell to place the header in, before you actually drag a header onto the page.
Similar to a button, the header option can only be placed in the page header, with the same set of features the normal button provides.
The advantage is that the header is always visible, whether or not the user has scrolled down on the page.
A simplified header for pop-up pages that replaces the commonly used side-bar menu button with a single purpose back button.