Content visibility is about controlling who can see your blog content. there are several ways to set the visibility for your content, you can set the page/post for a public, private or password protected.


there is 3 option that you can set from the Edit screen, the option is available under the Publish option, usually in the top right in the editor page.


The default setting for post and Page visibility is Public. Public visibility means that the content will be visible to the outside world as soon as it is published.


Content Visibility Location


By clicking on the edit link next to Visibility: Public in the Publish options, you can see the other option. The options are:

  • Public: The default, viewable to all.
  • Password Protected: Clicking this radio button followed by "OK" causes a further text box to appear, into which you can enter a password.
  • Private: This option hides the content from the public completely. Only can be access by site admin.


Here is the location of this option.



Password Protected Content 


Password Protected content is not immediately visible to the outside world. the only visitor who has the password can see the whole page. Instead, visitors will see a prompt similar to this:



The title for your protected entry is shown, along with a password prompt. A visitor to your site must enter the password in the box in order to see the content of the post or Page.


here is the step to Password Protect a Page or Post in your site.


Private Content


Private content is published only for your eyes, or the eyes of only those with authorization permission levels to see private content. Normal users and visitors will not be aware of private content. It will not appear in the article lists. If a visitor were to guess the URL for your private post, they would still not be able to see your content. You will only see the private content when you are logged into your WordPress blog.


A private post in WordPress is not visible to the public. Only logged in users with right permissions can see it among your blog posts. This is the view of private page by the public.


Any user who has the permission to publish a post can write a private post and publish it. The post will be visible to the user and following user roles.

  • Administrator – Can create, edit, and delete any private post created by any user on a WordPress site.
  • Editor – Can create, edit, and delete any private posts created by any user.
  • Author – Can create, publish, edit, view and delete their own private posts. They cannot see private posts created by other users.


here is the step to make Private page/post in your site.



Once you change the visibility to private, the post or page status changes to "Privately Published" as shown. Private posts are automatically published but not visible to anyone but those with the appropriate permission levels (Editor or Administrator).



 


WARNING: If your site has multiple editors or administrators, they will be able to see your protected and private posts in the Editscreen. They do not need the password to be able to see your protected posts. They can see the private posts in the Editposts/Pages list, and are able to modify them, or even make them public.


Source:
http://www.wpbeginner.com/beginners-guide/how-to-create-a-private-post-in-wordpress/
https://codex.wordpress.org/Content_Visibility