It's just a discussion under a Hive comment. Which the First Context app is able to "format" in a more presentable way, with resources for people to check, etc...

I think the idea is that you can start a particular "discussion" on anything, web2 things or web3, and have all that discussion recorded on chain.

Sort of keeps it tidy so that you don't have to go search on your notifications where was that comment about that thing... for me for example its a pain to do that because I have a tons of replies per day.