Complex sentence: In reggae, the DJ (deejay) is a vocalist who raps, "toasts", or chats over pre-recorded rhythm tracks while the individual who helps the DJ by selecting tracks to be played is called the selector.
Split into simpler sentences: In reggae, the DJ (deejay) is a vocalist who raps, "toasts", chants or chats over pre-recorded rhythm tracks. The individual who helps the DJ by selecting tracks or records to be played is called the selector.