In African countries, coffee beans are graded by size. You can easily tell what size (i.e., class) the bean is by the two letters after the name:
The AA, AB, and other classes used to classify lots in Kenya are just an indication of the sieve size. The AA grade in Kenya is equivalent to the 17 or 18 (17/64 or 18/64 inch) sieve size used in other countries of origin. AA grades often fetch higher prices at auction, although this grade is not an indication of cup quality and an AB lot from a better farm may have a better cup.