It is used to know how writing can be improved by synonyms. Enrich language, avoid repeated words, pinpoing errors, correct monotonous language. Users can easily avoid too long words (too academic) or too short ones (to simplistic) for better readability or for higher academic level. It also includes Profane Language and Slang Usage detectors to elude informal language if needed.
Another aspect of the product that is worth mentioning, is the Present Continuous Usage feature, which detects when the user's text exceeds the acceptable values.