If you make an event private or password protected, you will limit who can see either the event or the details of your event.
Making the event private will only allow your WordPress Editors and Administrators to see the event. Making the event password protected will allow you to set a password for your users. They will have to use the password to view the event details.
To make an event private or password protected, go to the “Publish” pane at the top, right hand side of the “Add new event” or “Edit event” screens. In “Visibility”, click on which level of visibility you prefer.