This is the name for a feature of the API dataset. They help make the contextual information that Wikimedia editors use to make their editorial decisions more understandable within an API feed. In other words, translating now two decades of editing behaviors into data. For a full essay documenting the nature and purpose of this, see its dedicated documentation page. This feature is not filters, rankings, or value judgements of “good vs. bad edits”. Nor is it an AI making decisions about content accuracy, truth or quality. A full list of fields can be drawn from in the creation of any given “signal” is listed at https://www.mediawiki.org/w/api.php.