Complex sentence: Burnett was good friends with the late Lucille Ball and Beverly Sills, and remains good friends with Julie Andrews, Betty White, and the late Jim Nabors and is the acting mentor to her protégée Vicki Lawrence.
Split into simpler sentences: Burnett was good friends with the late Lucille Ball, Beverly Sills, and Jim Nabors, and remains good friends with Julie Andrews and Betty White. She is the acting mentor to her protégée Vicki Lawrence.