The Pages list displays in two different ways, depending on your context.
When you open a Lightning page from the Lightning App Builder list page in Setup, or by using the Edit Page option from the Setup menu, the Pages menu shows the last 10 modified pages.
When you edit a Lightning app, the Pages menu shows all active Lightning pages associated with the current app, including record and app pages assigned to the app, and all Home pages that are assigned to a profile. You can sort the list either by page type or last modified.
Click a Lightning page in the list to open, edit, and save it, all in the context of the app you’re working in, while never leaving the Lightning App Builder. At the bottom of the page list, you can create pages or open existing pages, even ones not associated with the app.