Essentially it means just that, a report that is "out of the box". The phrase usually refers to features or things that are included with a product when it is provided or deployed.
Not out of the box refers to any reports that are custom made.
So reports that are included by default for whatever product you have purchased, be it Cost Transparency or CCM, etc would be considered "out of the box".
I unfortunately don't have any specific reports as an example for you.