"He knows her even though she does not know him."
Translation:Hij kent haar, hoewel zij hem niet kent.
If I understand it correctly, I think that "kennen" has to do with knowing or being aware of a person. "weten" I think means to know a piece of information.
As a native English speaker, it feels weird to me that there are multiple words for different kinds of "knowing," but I think this is common in other languages.
edit: I found this thread: https://forum.duolingo.com/comment/6162310/Weten-vs-Kennen the first comment is very helpful and even has examples.