It was five centuries of settlement from the time of Eirīkr Þōrvaldsson through to the final disappearance of the colonies. Even now it is not certain what happened, only that the colonies were abandoned some time in the late 15th Century. it is still uncertain whether they starved to death, were killed in conflicts with the Inuit or whether they returned to Iceland (although the Icelandic records do not mention the return of the Greenlanders).
Greenland in the Norse period was very slightly more appealing than it is now (i.e. not very) and supported a borderline pasture economy which the Vikings brought from Scandinavia. You grew grass, raised animals, produced milk and ate the animals. But it was very, very marginal. Even in the good years the climate was never good enough to grow arable crops, so all grains had to be imported from their other colonies.
As the climate deteriorated, the Norse stuck to their pasture farming which become ever more unsustainable. They never adapted their lifestyle to one better suited to Greenland, so the colonies gradually dwindled until they failed entirely.
Much the same happened in Iceland, but there, conditions were just good enough that pasture farming could be maintained throughout the Middle Ages, but it was a wretchedly poor place right up until the middle of the 20th Century.