Warning: Econ crunch ahead.
Medieval serfs in England who were wage laborers would have a cottage and 4 acres of arable land given to them. This is basically his "wage" for working for his landlord. He farms his 4 acres on his own time. The so called "cottager". In addition, rights to pasturage for animals would be available in the commons. Probably about 5x of that per cottager (20 acres or so). A cottager could aspire to purchase his cottage and 4 acres and thus free himself of his day job under his landlord. He would probably have hunting/trapping rights in the forest too, but they might be limited (rabbits etc., not deer or boars) or just unlimited rights but only in portions of the forest.
Typical rents for additional acreage would be about 6.25gp (2 shillings 6 pennies) per year for arable land, assuming a British pound from that era is worth about 50gp. If the cottager were energetic or ambitious, or found himself with extra cash and wanted to hire laborers of his own to turn a profit he could do it in this way. Not sure of the value of pasturage, as some pasture land was unsuitable for farming, and other pasturage was simply farm land that was temporarily fallow.
Eventually wool became so valuable the lords simply kicked all the cottagers off of their land to tend sheep and feudal peasantry disappeared in England.
A yeoman would probably need 20 acres of arable land and about 100 acres of pasture to get that rank (owned by him). Keep in mind at some times you had to have the actual title to the land to get the rank. So if you had to mortgage to a lienholder and they held the title until it was paid off, you literally actually "lost title" and were no longer a yeoman. In some areas/times the exact acreage to attain a rank of yeoman was actually spelled out, and often put a requirement on the yeoman to maintain a militia soldier with a certain standard of equipment that could be called up in time of need (often the yeoman himself if he was fit and able - the classic yeoman English longbowman).
P.S. Old style farming left a surprising (to modern eyes) amount of land fallow (most of it, actually). It was the only way they knew of to fertilize it - with cow patties. They couldn't just turn crude oil into ammonia by the kilotonne and make fertilizer like we do nowadays.