Because Zen is so hard to explain here are some quotations that may help you get an idea of it:
The essence of Zen Buddhism is achieving enlightenment by seeing one's original mind (or original nature) directly; without the intervention of the intellect.
Zen is concerned with what actually is rather than what we think or feel about what is.
Zen points to something before thinking, before all your ideas.
The key to Buddhahood in Zen is simply self-knowledge.
To be a human being is to be a Buddha. Buddha nature is just another name for human nature - true human nature.
Zen is simply to be completely alive.
Zen is short for Zen Buddhism. It is sometimes called a religion and sometimes called a philosophy.
Zen tries to free the mind from the slavery of words and the constriction of logic.
Zen in its essence is the art of seeing into the nature of one's own being, and it points the way from bondage to freedom.
The central concept of Zen is meditation.