What does related discussion mean?

The related discussion setting means that we will collect all comments and replies under a post that is a hit, even if the comment or reply does not contain any of the synonyms of the keyword.

The idea behind this is that if a post is a hit for your keyword, all the comments and replies to that post are also related to that keyword. E.g: the post says “I like Coca-Cola a lot”, and the comment is: “Me too!” Even though the comment itself doesn’t include Coca-cola, it is about Coca-Cola.