A large piece of land can be subdivided into two or more portions depending on its size, and the portions sold. This can prove beneficial as it could generate more income if sold as portions than as a whole.
Perhaps you home is built on a huge plot of land and you don't need a big garden. You could subdivide the land and keep the portion with your house on it and sell a part as vacant land.
Subdividing land is not a quick or easy process. Before it can even be ready to be registered in the Deeds office months and maybe even years could go into the approval and drawing of plans phase. Certain requirements have to be met for the land to be approved for subdividing and it would vary depending on the restrictions in Title Deeds, servitudes and the various Municipalities.