The angels, not half so happy in heaven, Went envying her and me-- Yes!--that was the reason (as all men know, In this kingdom by the sea) That the wind came out of the cloud by night, Chilling and killing my Annabel Lee.
The speaker circles back a little bit, and directly blames the angels for killing his girlfriend. He says that he and Annabel were happier on earth than the angels were in heaven, and that made them jealous.
He repeats what he said in line 13, insisting that "that was the reason" why the wind came down and killed Annabel Lee.
The speaker is extra careful to point out that this isn't just his wacky theory, but in fact that everyone ("all men") who live in the kingdom know that this is a fact.
We don't get any new facts in this stanza, and the story itself doesn't move forward. At the same time, maybe we learn something about the speaker's mental state.
The fact that he circles back and repeats the story of Annabel's death might show us see how traumatic it was for him.
He can't seem to stop thinking about that moment. Also, we think this theory about angels killing Annabel because they are jealous sounds a little off the wall. Check out line 23, when he says "Yes!--that was the reason."
He sounds a little like a mad-scientist hatching a nutty idea. This will be important later, when things get even more bizarre.
Finally, notice how, even when Poe seems to be repeating himself, he's adding little changes and bits of new information. In line 17, the speaker directly mentions Annabel's death for the first time, when he talks about the wind "killing" her. Again, even when the story is simple, it's a good idea to watch every word Poe uses.