Imagine you have a box of chocolates and you promise to share them equally with your friend. However, if your friend doesn't eat them, then they don't lose out on anything, right?
Non-violation nullification of benefits is a concept that works in a similar way. It means that even if a trade agreement is not being followed exactly as it was agreed upon, the other parties aren't losing out on any benefits that were promised to them.
For example, imagine two countries agreed to trade wheat for sugar. However, one country decides to stop trading wheat, but instead starts trading rice. The other country may feel that this isn't fair, but as long as they still receive an equal value of benefit (in this case, sugar), there is no violation and the benefits are not nullified.
Non-violation nullification of benefits helps to ensure that trade disputes are resolved fairly, and that all parties involved receive the benefits they were promised.