What does O.A. stand for?
It stands for Original Angel, and it's the name that Prairie Johnson a.k.a. Nina Azarova (a.k.a., series co-creator Brit Marling) calls herself -- and what her group of teen friends are taught to call her as well. She explains the meaning during a crucial scene in Season 1, after which her adoptive mother slaps her in an Olive Garden. Iconic.
How did O.A. survive the gunshot from the Season 1 finale?
When we first meet O.A. in the Season 2 premiere, she wakes up in a hospital and seems oddly overjoyed that her nurse has never heard of Barack Obama -- until we learn that her plan worked: She'd successfully slipped from one dimension to another, entering her own body in a different universe.
If you recall, the first season of The OA ended with a botched school shooting. By performing the five movements together in the school cafeteria, Buck, French, Steve, Jesse, and B.B.A. distracted the would-be shooter long enough for him to be tackled to the ground. His gun went off, and O.A. was seen standing at the window, a bullet hole having cleared the window and gone through her chest. It seems like she's pretty dead, but then, in the final shot of the show, she opens her eyes and says, "Homer."
Hmmm?????? What?? All throughout the final episode, the group of kids who had befriended O.A. were racked with doubt over whether or not she had made everything up after French found all kinds of books about parallel universe theory and the Russian royal houses in her home. Could her story about Hap and the other angels be a fabrication? But, when it all came down to it, it was belief that won out in the end, and when their school was under threat, the five did the movements together to, at least, distract the shooter. At best, what O.A. had said about them -- that they can transport a soul to another dimension -- would actually work. As it turns out, it was all true.
What are the movements again?
The five movements are the interpretive dance motions that O.A. and the rest of the prisoners in Hap's dungeon found through their N.D.E.s -- Near Death Experiences -- and were "given" to them by an interdimensional being known as Khatun. It's like Happy Meal toys, or Pokémon cards: Collect all five, and you have the power to travel between worlds. Okay, so, not exactly like Happy Meal toys.