The character, known as Moff Mors, is described by the website as "an Imperial who has made some very serious mistakes," but is still considered to be "an incredibly capable leader and spends much of the book working hard to prevent absolute failure." It's noted that "[Moff Mors] also happens to be a lesbian."
Lords of the Sith editor Shelly Shapiro first spoke about Moff Mors' introduction to the Star Wars universe on the Full of Sith podcast, stating: "This is certainly the first [LGBT] character in canon.
"But there was a gay Mandalorian couple, so it's not brand new," Shapiro continued. "It's not something I really think about, it just makes sense. There's a lot of diversity-there should be diversity in "Star Wars." You have all these different species and it would be silly to not also recognize that there's a lot of diversity in humans. If there's any message at all, it's simply that "Star Wars" is as diverse (or more so because they have alien species) as humanity is in real life and we don't want to pretend it's not. It just felt perfectly natural."
While Moff Mors may be the first fully-fledged LGBT character in the canon, same-sex relationships have been tackled in other Star Wars titles. BioWare's early Star Wars endeavor, Knights of the Old Republic, included one gay female party member, Juhani; However, her relationship with female players was minimal. Likewise, in the novel Legacy of the Force there is reference to a same-sex Mandalorian couple. For more on the significance of diverse characters you can read David Gaider's opinion piece for Polygon, A Character Like Me, about the importance of integrating new types of characters in video games.
Lords of the Sith releases on April 28.