It gives the gyroscopic visual effect of parallax declination between the springboard icon layer and the wallpaper layer when the device senses it is being tilted.
To access this option, open the setting app:
From there you will see your current wallpaper choice, and toward the bottom you have 2 choices:
Choosing the perspective view will separate the springboard icon layer and the wallpaper layer. Then, when you go back to the springboard, tilt your device and you will see the parallax effect: