Complex sentence: Cue Lights are used for back stage cues when a headset for communications is impractical, such as when an actor needs to make an entrance, or if there is a cue needed on stage where you need to be silent to avoid the audience hearing voices.
Split into simpler sentences: Cue Lights are used for back stage cues when a headset for communications is impractical. This is used if there is a cue needed on stage somewhere where you need to be silent to avoid the audience hearing voices.