Complex sentence: Coaches Adam Levine and Blake Shelton are joined by Alicia Keys and Miley Cyrus, who replaced Pharrell Williams and Christina Aguilera, thus making it the first season to have two female coaches.
Split into simpler sentences: Coaches Adam Levine and Blake Shelton are joined by Alicia Keys and Miley Cyrus, who replaced Pharrell Williams and Christina Aguilera. This is also the first season to have two female coaches.