sleem is right (Y) its used to negate nouns/adjectives/adverbs the other articles are لا "present/imparative negation" لن :future negation" لم "past negation" quite simple when you read more and write more you will get used to it

Think about لَيْسَ as a verb "to be not", in Arabic there is no verb "to be" but there is "to be not" For لا it is used to give the negation to a verb, wether to give a general idea about something that one doesn't do, e.g : لا يذهَبُ الى السُّوقِ he doesn't go to the market, so we have an idea that he generally don't go to the market. Also, لا is used with a present verb. It can be used with the same construction (لا + present verb) to give an order to "not do" : لا تَذْهَب الى السُّوق = Don't go to the market. As for لَيْسَ , it's already a verb, so it needs to give the negation to a noun / adjective.

لا is an article which help you to negate or to make an order in an other context ! look at these two examples and their different translation : لا يذهب = he doesn't go لا تذهب = don't go but , you have to use them before a verb. as for لست ; which includes the verb ليس and the pronoun ت ; it alway goes with nouns or adjectives ; for example , أنا لست سعيدا = I'm not happy . if you need more explanation ; just let me know

لست means "You are not" Simply... so the whole meaning is " You are not an American" No means لا uses to negate a yes or no question. Let's say that you said: "I'm an American." And some one reply back: : "No, You are not an American" Translation: YOU: أنا أمريكي THE PERSON: لا ، أنت لست أمريكي

No = لا You are not (male) = لستَ You are not (female) = لستِ You are not (2 person) = لستُمَا You are not (more than 2 person, male) = لستُم You are not (more than 2 person, female) = لستُنَّ