The significance of the Homestead Act was that it helped to cause the settling of the Great Plains (and, to some extent, more western areas).
The Homestead Act offered free land to anyone who would settle it, improve it, and live on it for five years. This offer attracted large numbers of settlers who moved to the Plains to take advantage of the free land. Historians tend to emphasize that this law did not actually end up helping small farmers as much as it was supposed to. They point out that the land grants were often not big enough to support farmers. They also point out that speculators often ended up with the land, thus benefiting rich people rather than the small farmers it was intended to help.
Homestead Act of 1862 was significant because it encouraged the settlement of the Western frontier, The act permitted any citizen or prospective citizen to claim 160acres of public land and to purchase it for a small fee after living on it for five years.