By exposing the whole scene at the same time. All pixels collect light at the same time and expose at the same time. At the beginning of the exposure, the Sensor begins to collect light. At the end of the exposure, the light collecting circuit is cut off. The Sensor value is then read as a photo. CCD is the way Global Shutter works. All pixels exposed at the same time.

The advantage of global shuter is that all pixels are exposed at the same time. The disadvantage is that the exposure time is limited, and there is a mechanical limit of the minimum exposure time.