In the videogame anyways, Macbeth's people have a strong feudal/monarchical society where the king divides up the land to various lords. Then there are knights, sons of nobles, who serve either the king or a lord, followed by groups of footsoldiers from poor families which are each under the command of a knight, and serfs who live on and farm the lord's land. A serf would be like a peasant class but with less rights and somewhat closer to a slave, except they don't typically enslave their own kind because of their pride. There's a huge class divide where the poor are extremely poor and the rich are extremely rich, a fact that rarely changes for individuals or families.