Wakeboard ballast is essentially an additional weight that you use inside your boat in order to ensure it is correctly weighted and to help it cut through the waves rather than bouncing on top of them. This is very important to a beginner when wakeboarding as it means that the boat will be more stable and so the rope will swing around less and stay taut. As such they will be able to ride across the water and do jumps etc more easily without being thrown about by the boat as it rocks.
Thus the two main items you will need to look into as a beginner at wakeboarding are the wakeboard itself and ballast/fat sacks. On top of these are the obvious things such as a wetsuit that will keep you warm and healthy (and mean you can wakeboard in any weather), sun cream, a towel and probably a camera to capture some of your more exciting and fantastic moments. With that you’re ready to get started and can begin adding to your equipment or buying more advanced items as you progress.