From the University of Central Florida Libraries:
https://guides.ucf.edu/c.php?g=78201&p=512377
"Every guide in the system that is "Published" will appear in the system directories. If the LibGuides created for all of the individual courses are included in the directories, they will obscure the other listings. For example, imagine if the A-Z list of guides included 30 different ENC1101 guides created to meet the needs of different instructors and sections.
If you create a guide for a specific course, change its status to "Private" when you're ready to make it available. You can share the URL with the instructor and the students. If you intend for the guide to be used by those students beyond the initial class session, also provide the link to the library instruction coordinator so that a link to it can be added to our "Course & Department Resource Pages" LibGuide. You can also create a link to the specific course guide in other locations, but consider linking from those locations to the appropriate section of the "Course & Department Resource Pages" LibGuide to reduce the need for updating those other locations. For example, here is a link to the Nursing section of the Course & Department Resource Pages.
Another use for publishing a guide privately is when you have created part of the guide and would like to test out the internal links. Although the guide may not be ready for public consumption, nobody is going to accidentally stumble across it because they would have to know the URL."