Wisdom is the combination of experience, knowledge and careful judgment. If you've got it, you're "wise." If you haven't, well don't worry, most of us don't either.
Wisdom is also the term we give to the sum total of a culture's knowledge and application of that knowledge, acquired over time. We talk about "the wisdom of the ancient Greeks," for example, meaning everything about their culture from their scientific and philosophical discoveries to the art and culture they created. Don't confuse wisdom with knowledge — which is merely the accumulation of facts with no sense of what meaning to make from them.