I think if you understand something really well (anything: the law of gravity, the Curry-Howard isomorphism, electrolytic dissociation, general relativity,...), you can find a bunch of comparisons, or metaphors, or other ways to explain it so that an interested five-years-old will get a rough idea. A very rough idea indeed, but one that could allow them to ask qualitatively reasonable questions, and that forms an intuition which helps during a real study.

The "interested" part does a lot of lifting though. It's really hard to explain things to uninterested people.

If the person you are explaining your project to is not interested in the technical side, presumably under the rather confused but popular theory that technical aspects are not relevant to technology ventures, you'll not be making headway. It's much better to just make up some dollar numbers and run with that.