"Enlightenment for a wave in the ocean is the moment the wave realises that it is water."
Wisdom in Buddhism can refer to two types of insight: conventional wisdom and ultimate wisdom:
Conventional wisdom relates to understanding the conventional world, or the world as we know it. Traditionally it refers to understanding the way in which karma functions; to understand which actions bring us happiness and which bring us suffering. Conventional wisdom covers all understanding of the world as it functions, including science, with the exception of ultimate wisdom.
Ultimate wisdom (jñana in Sanskrit) refers to a direct realisation which is non-dualistic, and contradicts the way in which we ordinarily perceive the world. The experience of ultimate truth or emptiness is beyond duality.
It is important to remember that emptiness here does not refer to nothingness or some kind of nihilistic view. Emptiness refers to the fact that ultimately, our day-to-day experience of reality is wrong, and is 'empty' of many qualities that we normally assign to it.
Describing this non-dual experience in words is not really possible, as language is based on duality and contrasts. Trying to explain this experience - which contradicts our normal perception - is a bit like explaining colours to someone who is born blind; difficult to say the least.