Star Wars officially confirms General Leia Organa is the one training Rey in The Rise of Skywalker. Over the course of the sequel trilogy, Rey's found mentors in the returning legacy characters from the original films. In The Force Awakens, Han Solo served as a father figure to the young scavenger, while Luke Skywalker taught her in the ways of the Force during The Last Jedi. Of course, both Han and Luke are now dead, so Leia is the only living member of the old big three Rey can turn to for guidance (Luke can still appear as a Force ghost to provide words of wisdom).
At one point in time, there sadly was only a limited amount available for the team to use. Despite the fact Leia's role needed to be significantly altered, Abrams is still making sure Rey has a teacher in the Resistance general.
Screen Rant attended the Rise of Skywalker press junket, where costumes from the film were on display. Small plaques with character descriptions were part of the exhibit. Unsurprisingly, Leia's mentions her leadership role in the Resistance, but also confirms she's doing some Jedi training on the side:
General Leia Organa continues to lead the heroic Resistance, building back a fighting force after having suffered costly setbacks. Leia is also training Rey in the ways of the Force, for the galaxy still has need of a Jedi.
This development could partially explain departed Star Wars 9 director reveal Leia as the last Jedi in the film, but due to Fisher's death that is no longer the case. Still, it seems to be an idea Abrams and co-writer Chris Terrio were ionate about, and they wanted to find a way to implement it in some capacity in the final product. After all, Rey is still young and could definitely use a teacher as she grows in power and fine-tunes her abilities. While Leia never became a Jedi, she is the best (only?) option to teach Rey since she's Force sensitive and has tapped into her power before. Her experience is limited, but Leia and Rey will have to make the best of it.
Scenes of Leia training Rey probably take place on jungle planet Ajan Kloss, where the Resistance appears to have set up headquarters in The Rise of Skywalker. It should be interesting to watch Leia instructing Rey, as fans will have an opportunity to see General Organa in a new light. Leia has always been a fierce and determined leader wise beyond her years, but she's never been called upon to instruct a powerful Force . Coupled with her responsibilities in the war, it isn't out of the question to wonder if Leia isn't fully prepared for Jedi training and she's in danger of spreading herself thin. Teaching Rey will undoubtedly be a challenge for Leia, but after all she's endured, odds are she'll come through again.
