In the context of the page settings in Shogun, 'Public Visibility' toggles the "Navigation Menu' checkbox found in BigCommerce, which determines whether the page in question is shown in the Navigation Menu.
By default, this toggle is set to 'off' but can be toggled 'on' if the intent is to show this page in navigation.
Note that if in Shogun this is 'off' but in BigCommerce it is 'on', republishing the page in Shogun will turn it off again, so we recommend ensuring the same state is set consistently across any given page.