If you wish to create pages on your website that you do not want to either display in Navigation 1 or Navigation 2 i.e. you want to link them from elsewhere, then you can add them under "Unlisted Pages" section (formerly called as "Extra" in older SF versions).
1. Click on Unlisted pages (Extra) at the Left tree menu
2. Click on the "+ Page" button or F8 to add a Page underneath it.
3. Ensure the page is set as 'visible' (not hidden)
These pages will not display in your navigation menu unless you specifically create a link to the pages under "Unlisted pages".
**Save and publish your shop.
**You can add a link to this extra page in Navigation 1 or Navigation 2 using the Insert Link... feature -> select "Link to a place in this website..." and choose the extra page.
**Or, to get the exact URL of this "extra" page, you can open the page properties and copy the page filename - locate the "Page ID" section and you will find the page filename - highlight it and press CTRL+C
To open this extra page, go to your website and then navigate to a page - edit the page filename to the extra page filename.