Something experiential comes from the real world — from experience. Experiential things can be seen, touched, and verified.
Some knowledge comes from reading about it. But experiential knowledge comes from actually doing and experiencing it. If you learned to sail by spending every summer on the water with your own boat, then you have an experiential understanding of sailing. If something is experiential, it's real, rather than conceptual. But you can't learn everything experientially. That's what books are for.