As a general example. Let’s say you have five menu headings Home, About, Commercial, Editing and Contact. Each menu page link when clicked takes you to that specific page. These are your main focus pages. They fit neatly in one line on the menu.
Now you want to add several additional pages and they are called Experience, Our Equipment and Our Team. If you add these they will appear in the main menu and as you add more pages the menu becomes cumbersome. Plus they play a supporting role but not the main focus.
So if you uncheck view in the primary menu (page settings) on each of these three new pages, save the project and try to preview it. They will not be visible - they are hidden.
Anybody looking at your site will only see the initial five headings: Home, About etc. They will not know they exist. You can get to them via the upper right corner menu dropdown.
Now if you create a dropdown menu in the class manager and put Experience, Our Equipment and Our team in a new menu within the About page they will be visible (dropdown) when someone clicks on the About link. The three pages are now visible. That would be one example.
In say case my site will have photos specific to Realtors, Property Mgr and Commercial. Each focus is different and has specific photos. These photos are examples of my work. The hidden page would only be accessible if they click on a button or text link. With the questions “Would you like to see more photos”? or something like that. When they click that button it takes them to my hidden page. The images on this page are creative but not related to the specific categories.
Hope this helps.