"НЕ" is a Russian word that translates to "not" in English. It is used to negate verbs, adjectives, and other parts of speech, indicating the absence or opposite of something. For example, in the phrase "Я не знаю" (I do not know), "не" negates the verb "знаю" (know). In addition to its grammatical function, "НЕ" can also be used for emphasis or to express disagreement. It is a fundamental part of the Russian language, essential for forming negative statements. Understanding how to use "НЕ" correctly is crucial for effective communication in Russian.