It allows you to shoot a panorama 360° in every direction, by stitching together multiple shots that you take whilst turning on the spot. This creates a spherical 360° panorama, which allows you to look around in all directions instead of just horizontally.
A gyroscope is a sensor that can be used to either measure or maintain the orientation of a device. Traditionally, they were built using a spinning rotor to detect changes in orientation, eg. twisting or rotation.