I will explain that to you right here.
There are two types of page restrictions, viewing restrictions and edit restrictions. You can learn more about this subject on this page here in the forum: How do I restrict a page so that user users or user groups can’t see it?
Viewing restrictions are inherited, which means that a viewing restriction on a page will be applied to the child pages as well. Edit restrictions are not inherited, meaning that every page needs to be individually restricted.
The restrictions dialog shows you if there are inherited restrictions. In view mode on a child page, click on the restriction symbol and then on the “inherited view restrictions” link to see these restrictions.
You may watch our Video #83 Inherited restrictions of the Video Tutorial Series “Learn Atlassian Confluence” and also read more about restricted pages in Atlassian’s documentation on this page: Page Restrictions.