For better or worse, grains (rice, wheat, barley, millet, etc.) form a large part of the human diet and provide most of the carbohydrates consumed globally. To store large amounts of grain without rot, it must be harvested when dry and kept dry for shipping and distribution. Once water hits grain, which are basically seeds, they will start to sprout. Typically this happens when a seed or grain falls to the ground and a new plant starts to grow. You might buy bean sprouts at the store, or sprout them yourself. By sprouting a grain in your kitchen, you are starting the break-down process preemptively. Sprouting a grain releases certain nutrients (iron, zinc and vitamin C), and boosts available protein and antioxidant levels (link here). You are also decreasing the amount of phytic acid (plant defense system) which inhibits mineral absorbability in the grain before you eat it.
To sprout a grain, buy organic, wash and drain them and put them sideways in a jar with a fabric membrane on your counter. Within 3-5 days, the sprouts should be showing and they are ready to eat. If they smell off in any way, toss them and try again. This is a good link on how and more details on why.