This is a property of type Page, and refers to a page on AcaWiki with a summary of a work. The property is to be used in a page with a summary of another work, and the use of this property is meant to indicate/record that the second work states or implies or is inferred to have a disagreement with the methods, data, findings, or conclusion of the first work.
To use this syntax, both works must have pages representing them in AcaWiki. It would be possible to make a Property:DisputesURL to record a dispute with a work that is not in AcaWiki but has a URL. Would that be useful? Not clear yet.