Single quoting lets you pass a list without evaluating it.

(car (eval '(a b c))) vs. (car (a b c))

Do the same thing.

Have you read SICP? Somewhere in the 1st-3rd chapter there's an explanation of first-order evaluation that scheme uses. Once you know how scheme evals sexps, it makes sense that quote skips some of the steps of evaluation. I strongly recommend the SICP/Little Schemer/Seasoned Schemer if you haven't heard of them.