Complex sentence: Brian Douglas Wilson (born June 20,1942) is an American musician best known as the chief songwriter and co-lead vocalist of the Beach Boys, and also functioned as the band's main producer and arranger.
Split into simpler sentences: Brian Douglas Wilson (born June 20,1942) is an American musician. He was the chief songwriter and co-lead vocalist of the Beach Boys, and also functioned as the band's main producer and arranger.