This is a very vague question because there are many things that could be said about the Spanish colonization of North America.
One thing that can be said about the Spanish colonization is that it came on the back of the military conquest of the Aztec Empire. This conquest was possible in part because of the technological advantage that the Spanish had and in part because of the fact that the Spanish were able to find many native allies who hated the Aztecs.
The next thing that is important to say about the Spanish colonization is that it created what some historians call a “frontier of inclusion.” What this means is that the Spanish typically incorporated the Native Americans into their society. There were not really enough Spaniards coming over to colonize and so they could not form societies that were made up only of Spaniards. Instead, they included the natives, in many cases intermarrying with them. The natives and the mestizos (mixed-race people) were not seen as equal to the Spaniards, but they were included in Spanish society.
Finally, we can say that Spanish colonization did not manage to lead to democratization. The Spanish did not set up democratic institutions. This was in part because Spain was not democratic and in part because of the inequalities between Spaniards and non-Spaniards in the colonies.
These are some of the important aspects of the Spanish colonization of North America.