In "Return of the Jedi," it means return of the Jedi Knights. In the books that follow, Leia becomes a Jedi, Mara Jade (Luke's wife) becomes a Jedi, Luke's nephews Jacen & Anakin become Jedi, Luke's neice Jaina becomes a Jedi, Kyp Durron (one of Luke's trainees) becomes a Jedi, and Luke trains a whole new Jedi order after the one of the Old Republic. Ta-da! That pretty much explains it.🙂