You can access the page actions menu by hovering over a page on desktop, or long-pressing it on mobile:
This menu allows you to make various changes to your website's pages:
This allows you to copy any page within the system. All modules, text and settings from the original page will be duplicated as a copy.
Any page except for the homepage can be turned into the homepage. This can be handy for switching on / off seasonal pages of your site. This will make your selected page the new homepage and the homepage is copied into the original page you selected.
This is an SEO specific setting which allows you to create a page-specific description, which Google may or may not choose to display in the search results for your site (should they decide to show section links in your search result).