Service Desk Issue Reminders adds a notification to the Jira header that displays the amount of issues in Jira Service Desk project projects that don't have an assignee and have not yet been resolved(or otherwise closed) yet.
By hovering Hovering over the notification will open a dropdown will open menu which shows a list of containing the amount of open unresolved and unassigned issues for each service desk project. You can learn more about reminders here.
After clicking on one of the notifications reminders in the dropdown you'll be redirected to a list of those issuesunassigned and unresolved issues for that project. Note: This can be changed to redirect you to the project's queues page instead. You can read more about this here.