Coffee beans are in fact seeds. They are the seeds of a cherry which grows on a bush.
The majority of coffee is grown close to the equator, where there are high growing temperatures. Many coffees also benefit from growing at high altitudes as the high temperatures during the day and low temperatures at night encourage the growth of better quality coffee cherries. Although, when grown at altitude it is often harder to farm these coffees therefore not only are they a better quality but they will also be a higher price to farm.