The Walking Dead has finally begun exploring the cryptic labeling of "A" and "B" that have appeared throughout the AMC TV show, which Jadis and her associates in the mysterious helicopter use. After first teasing the helicopter early in season 9, The Walking Dead explained more of the "A" and "B" labels in the latest episode, "What Comes After."
A connection between the helicopter sightings and the "A" and "B" labels has been teased for a few seasons now, but it was only earlier in season 9 that The Walking Dead confirmed there was something to the theory. First, it was revealed that there is, indeed, a helicopter frequenting the area near the garbage dump, and Jadis is familiar with where it comes from and what it's doing. Next, in her conversation with Gabriel, Jadis reveals she had been collecting people and handing them over to those in the helicopter - a trade she made in order to receive important supplies. During that conversation, Jadis also confirms that the cryptic "A" and "B" are classifications, but she doesn't elaborate beyond her observation that she always thought Gabriel was a "B" and not an "A".
In the two Walking Dead episodes since, even more has been revealed about what "A" and "B" might mean. After capturing Gabriel (her "A"), Jadis attempts to kill him or infect him (or both) in the same manner that she tried with Negan in season 8. Jadis eventually lets Gabriel go, so when she attempts to rendezvous with the helicopter in the next episode (which was also Rick Grimes' final episode), she has to lie about having an "A" to trade. However, just as she's about to be picked up, Jadis sees Rick washed up on the river bank. She radios to the helicopter that she doesn't have an "A", she never did, but she does have a "B" - Rick, adding that he's a friend who once helped her and now she wants to return the favor.
Considering that Andrew Lincoln won't return to The Walking Dead TV show, it's entirely possible that audiences may not see or hear more from Jadis until AMC's Walking Dead movies air, in which case, it could be a while before viewers learn any more about these letter classifications. Still, it's easy to speculate more thoroughly on what "A" and "B" might mean given what's been revealed thus far. For instance, the scene in which Gabriel confronts Jadis introduces the idea that "A" and "B" might refer to a person's attitude or abilities - with "A" implying the person is a leader type, like Rick or Negan, and "B" being for someone who is a follower, like who Jadis thought Gabriel was until he stood up to her.
However, now it seems it isn't all that simple. An "A" might still refer to someone who won't follow orders, but it seems to also involve attacking them with a walker. Whether that is for the purpose of turning them in to a walker or just a sick means of intimidation isn't clear, but it appears to all be a part of this whole "A" process. Now, Jadis' earlier conversation with Gabriel didn't reveal much about "B", but her decision to rescue Rick does. Considering his condition, the "B" might refer to an injured person, which would make sense given that Gabriel's eye condition and him originally being considered a "B".
With all the information currently available, those are the best theories out there right now - "A" referring to an individual who will not go willingly and must instead be either turned or intimidated into going; a "B" referring to an individual who chooses to go and possibly injured. Whether or not the person who delivers the "B" is rewarded in the same way, Jadis was for her "As" remains a mystery, but her decision to bring Rick along suggests having someone in tow is key to gaining entry. Perhaps the "Bs" are then also tasked with collecting more "As"? Whatever the truth of this "A" and "B" business is, The Walking Dead won't be offering up any more answers anytime soon.
The Walking Dead season 9 continues this Sunday, November 11 with "Who Are You Now" on AMC.