With the page builder you can edit any element on any page of your site.
There are three kinds of elements that can be added to pages: sections, components and blocks.
Sections are groups of elements that are grouped in a horizontal box on your page such as heroes, navigation bars, call to action etc.
Components are elements that have properties that can be edited when clicked, elements such as images, headings, paragraphs etc.
Blocks are groups of elements that are used as quick templates that can be droped on the page such as contact forms, product or post lists, carousels, sliders, image galleries etc.