An overview is a customisable way of displaying only relevant linked issues on the current issue.
In addition, it's possible to edit any displayed custom fields, following the right current user's permission
You can configure one location by overview from the following list but you can configure multiple overviews for one project.
Jira Software and Jira Service Management Agent locations
Issue Glance view
Issue Panel view
Issue Activity view
Jira Service Management locations
For now, only licensed users with product access can use Elements Overview on Jira Service Management portal, read more for further explanation
How to configure an overview
In the following pages, you will find the full explanation of the 3-part overview configuration.