There's zero context for what he's talking about. And he doesn't help much by going off on a million tangents and trying really hard to be cool.
And opening with "Hello! Is this dog?", a bunch of empty space, and then half a picture of an old meme is kind of dumb. I mean, I had to scroll down a screen just to find out the article was confusing and written badly.
If you stick with the article for just a minute you get plenty of context, and if you're still confused, there are a ton of links in there to find out more. The million tangents is his usual style, and maybe not for everyone. However, the article is a comparison of specific implementations of generators (to give insight to the ES6 proposals) and a review of new iterator literature, with a bit of an introduction to them to get everyone on the same page. There are plenty of more gentle introductions to generators; this really isn't for the same audience.
> Wow, what a terrible article.