what does unresolved mean?

The basis of saying that something is "unresolved" means that there are still unanswered questions to the subject matter that you are trying to deal with or "resolve". It means, whatever thats discussed has not reached a satisfactory conclusion. Thus, it remains a subject that requires further thought.

It means the discussions that you havenot picked the best responses yet. When you pick the best response, then it will be gone from the unresolved discussions.