You created a C# script class, called MusicManager, and added an instance of this class as a component to the Manager GameObject. Additionally, you also created two GameObjects, called music1_medieval and music2_arcade, in the scene, with each containing an AudioSource component linked to a different music clip.
The script class has two public AudioSource properties: Music Medieval and Music Arcade. At design time, we associated the AudioSource components of the music1_medieval and music2_arcade GameObjects with these public properties.
At runtime, the Update() method is executed in every frame. This method checks for the UP/DOWN/RIGHT/LEFT array keys being pressed. If the UP arrow key is detected, the medieval music audio source is sent a Play() or UnPause() message. The Play() message is sent if the clip is not already playing (note that its time property is zero). In comparison, if the DOWN arrow key is pressed, the medieval music audio source is...