Flash synchronization is the process with which a photographer syncs the flash of the camera with the speed of the shutter located in front of the electronic sensor. Have you taken pictures where the flash and shutter are not synchronized and ended up with a partially illuminated picture? Probably yes.
But flash sync is not complicated. Most digital camera these days have a built in function where you can adjust flash and shutter speed. If you have an external flash mounted on the camera, increase the speed of the flash to keep up with the shutter speed. The result will be a well-illuminated picture. If you use a flash from a well-known company such as Nikon or Canon, you will have a super flash in your hands. The technology used in manufacturing these devices emits bursts of light at quick intervals. High-speed flash sync makes it difficult to detect the separate bursts, but the results are spectacular.