Washing beans removes the skins of the berry of the coffee bean and leaves it clean and green.
After washing, the beans have to be dried to remove excess water from the beans before they can roasted or transported. Drying has various techniques and styles, each producing different flavors and tones in the bean. You can also ferment the bean before roasting, very popular and trendy at the moment.
Fermenting introduces a wealth of different and unique flavors in coffee. Very similar to how grape juice is fermented to wine.