The Objective Revision Evaluation Service (ORES) is a service that provides scoring for revisions. For example, the score indicates the probability of an edit being vandalism. If you want to see what the API does, you can try scoring an edit like this:
You can read more about ORES in Wikidata in this blog post (English).
You can use the ORES review tool by enabling it in Special:Preferences#mw-prefsection-betafeatures.
There is some vandalism we miss and some non-vandalism that we flag. We'll be working on the prediction strategy to improve accuracy over the next couple of months. In order to help us you can report mistakes flagged by ORES on this page.