Meaning of the original Hebrew of "thou shall not" in the ten commandments

I noticed that in German (Luther's translation) it says "Du sollst nicht" for "thou shall not." To me, this sounds more like "thou should not," which makes more sense to me, because if the Almighty says "thou will not" or even "thou may not" it stands to reason that to do so would be impossible. Saying "thou should not" makes more sense to me because it implies that you have the ability to disobey. I guess I am sort of asking for a short lesson on ancient Hebrew grammar of, as well as the original Hebrew (and English transliteration) of "Thou shalt not" as it is used in the ten commandments. I apologize if this is off-topic. I appreciate if anyone could answer or direct me to a good link.