It does not mean that. It means the time interval of "no sound" between sounds. So if I set that to 1 second and I had 4 sound files the sequence would be:
Sound File1 playing
Sound File1 ended
1 second interval
Sound File 2 playing
Sound File 2 ended
1 second interval
Sound File 3 playing
Sound File 3 ended
1 second interval
Sound File 4 playing
Sound File 4 ended
1 second interval