So I've found out about something, I can add some of my articles to series.

This thing is so hidden that you feel like you have found some rare item. You need to see your article on your blog and click to triple dots as you have seen above.
However, what's weirder is that it is plain useless. I mean, my blog does not provide a section to only show the series I have created, it does not explicitly put a label on the article to define which series the article is under. You just add your articles to series and, yeah, that's all folks.
Then I have thought that "Maybe it is an unimplemented feature? Maybe devs thought they will implement it later on and forgot about that.". What is "series" all about?
Mark
This is the announcement:
hashnode.com/post/create-a-series-to-group-your-a…
I have to admit to not reading it since I don't write blogs here, but maybe it helps.