translation:
We notice that you have already sent a number of replies (2) to helicoptur. Did you know that it was also possible to exchange direct messages with this person on our site? And Button "Direct message"...
This does not actually do anything. If you do click the button, then create a post, it's not a private message, it's public topic. I would assume there would be an option to turn this message off.
Yes I know it says that you can send a private message (direct message), but I've clicked the button, sent a message, and it was a normal post. I'm not the only one who's done it though. Other people (I think @mr_owlssssnap2) has tested it out before. None of the tests were private.