kefkaboo2003
The explanation given by Toritoribe is correct, but I thought I would give a little more detail.
the おう roughly translates as, "Let's...."
taberu = to eat
kuu = to eat
tabeyou = Let's eat.
kuou = Let's eat.
The interesting thing about tabeyou or kuou is that it can be used to refer to the actions of one person, two people etc., while the English "Let's...." only refers to two people or more. In Japanese, I can say, "Let's eat," when I am referring to only myself.