When you hide a menu item by changing the “extra capability” setting, it makes the menu inaccessible. Users who don’t have the selected capability can’t open the linked admin page even if they manually type in the page URL.
There is also a way to hide a menu item without preventing access. To do that, select a menu item:
And click the “hide without preventing access” toolbar button:
This will hide the menu from all users, but those who have the required capability will still be able to access the corresponding page. For example, you can reach the page by entering the URL in the address bar or by following a custom link.
To make the hidden menu visible, select it and click the same button again.