What is the Pure Land?
It depends on the school and/or the tradition a Buddhist chooses to follow. Just so you are aware, Pureland is really only a "school" in Japan. Everywhere else in Mahayana, a kind of Pureland practice is usually taken for granted, or at least not treated as its own separate practice, like in Chinese Ch'an, for instance.

The majority of the Buddhists who aspire to be reborn in any Pureland (there is more than one) usually believe it to be a literal place you go after you die if you aspire to be reborn there. Others use thoughts of Pureland as grounds for meditation and/or prayer. Others take it upon themselves in their Bodhisattva practice to make this realm a pureland. None of these are mutually exclusive either--all three practices can be undertaken by any given person.