Office 365 supervision policies can now make use of artificial intelligence and machine learning to detect offensive language in email and Teams communications. The data model covers a wide range of problematic language, but only in English. You can go ahead and cheerfully continue to swear in French, German, and other languages with no danger of being detected by policy.
Although Office 365 supervision policies are intended to monitor a subset of user communications, usually involving specific groups of people, you might want to use a policy to monitor all email. In that case, how do you make sure that your policy has everyone in scope? The problem is that supervision policies don’t support dynamic distribution lists, so you need to do some work to build and maintain a distribution list containing all user mailboxes.