Existence is everything that is. It holds within it all dualities - good and bad, right and wrong, saintly and evil, beautiful and ugly, and so on.
Experience is anything we go through using our senses - even the senses themselves. And the one who is aware of these experiences is the experiencer.
If we look closely, we can identify two fundamental aspects of existence: the experience and the experiencer. It's worth checking this directly - don't believe it just because it's being said. See for yourself. If we can find anything else in existence apart from these two, then this understanding won't hold. But if not, we can take this as a starting point.
The core realization is this: the experience and the experiencer are not separate. They are deeply intertwined, inseparable, and cannot exist independently of each other. When this is truly understood, it marks the end of seeking because there is nothing more to be known beyond this unity.
But just knowing this in our head isn't enough. Real understanding comes when this is seen directly in our own experience, supported by clear and honest logic.