The Hide From Viewer Macro is part of the commercial The projectdoc Toolbox for Atlassian Confluence plugin. It hides the text from users that do not have write access to a page. With this macro, authors and therefore most team members, are able to share information not to be shown to readers.

This is not a security tool! The information is still stored in plain text on the server (as this is true for the Hide From Anonymous User macro). The content is simply not rendered for the users lacking access permissions. But it will eventually be displayed for users who try to reveal it (e.g. through searches, previews, source code, history, etc.).