This plugin will create categories for pages only, different from the categories assigned to posts. It will also list these page-only categories on the WordPress Dashboard, so you can sort pages by category on the dashboard.
How can I make the page categories private?
Open the create-categories-for-pages-only.php file, locate ‘public’ = true, and change it to ‘public’ = false,
Here you can create new page categories.
On the dashboard you’ll be able to sort your WordPress pages by category.