The Publish (private) option allows you to subscribe to your Sakai calendar from an external calendar such as Google, Outlook, etc.
You can subscribe to the calendar in your Sakai Home area, and this will subscribe you to all of the events for all of the Sakai sites in which you are enrolled.
You may also subscribe to the calendar in a specific Sakai site. If you do this within an individual site, it will subscribe you to events for that site only.
Select the Calendar tool from the Tool Menu in your site.
Use one of the two generated links to subscribe in your external calendar application.