Anytime a person crosses a boundary — a legal boundary, a moral boundary, a physical boundary, or a binding business deal — that's a violation. When a burglar picks the lock on your door, that's a violation of your property.
A violation can be a disrespectful act or the crossing of someone’s physical boundaries. When you're forced to shake hands with your boss's wife, the way her perfume stings your eyes might feel like a violation. Violation is often used to describe an action that disregards an agreement or a basic right, such as a violation of a global climate treaty or a human rights violation.