This report enables you to extract the detailed specification of one or more Tests, so that you can generate a document that contains a snapshot of the latest specification. This can be used for revision/approval, or even to share it with someone else that hasn't access to Jira and wishes to pursue testing.
The information shown on the report depends on variables defined by yourself within the template, at the start of it. You can set them as you wish; please see the official documentation for more info.