Ops Reporting is a suite of shipping performance analytic reports that are run against your shipping data in Delivery Manager.
They provide you with an overall view of your delivery performance, whilst also providing specific details about how your carriers are performing against Service Level Agreements (SLAs) and whether customer promises are being met.
You should have already had an email telling you how to activate an account in a separate application called Looker - this is the platform on which the reports are run. Refer to What is Ops Reporting? for more details.