To skew is to turn or place at an angle. When you build a house of cards, you must slightly angle, or skew each card, so structure will stand up.
From the Middle English skewen ("swerve"), this verb was born to describe things in the physical world. Nowadays, though, we encounter it more informally: If you're in advertising, you might skew (target, aim) your commercials toward a particular demographic. Even before that, you may collect some statistical data on your intended audience, and then make sure that data is accurate, because bad or irrelevant info might skew (distort, inaccurately depict) the results of your research.