Quite simply the other half of the peasantry, Peasant Women are simply the farm girls: wives, daughters, aunts, and nieces, from various villages. For some of the women however life in the villages is boring or confining, and many have gone out into the world to make a name for themselves. For others, they have been forced by circumstance to join an army and fight, be it out of desperation or necessity.
While these women are poor fighters on their own, by the end of a fight or two, they'll have enough loot to trade for some basic armor and weapons besides stolen meat cleavers, knives, clubs and pitchforks, becoming Maiden Scouts.
They form the absolute bottom of the female mercenary tree, and while ordinarily not recruitable, they are exceedingly common sights in prisoner stacks where they can be recruited. Like their male counterpart, the farmer, they are next to useless and act as little more than a distraction. It is best to keep them out of the fighting so that they can be upgraded to scouts.