An issue can have 3 different statuses.

1. Active - The issue is live and available for the public to access through a direct issue link, title link OR accessed through the archives
2. Disabled - The issue is not live and any issue or title links will result in the below message:
   
3. Future Pub - The issue was set to become active on a future date at the time of upload.  You cannot change an issue to a status of future pub once the issue becomes active.

You can toggle between active and disabled statuses for an issue while in your issue settings and options screen (see screenshot below)

NOTE:  If your status is disabled, you will not be able to access the Enhance button directly from the manage titles/issues screen to navigate to the page editor, autolink management, batch update existing links OR page replace tool.  You will need to access that section through the Enhance button on another issue, then select your disabled issue from the dropdown menus (see screenshot below)