"Much" and "many" are determiners used to indicate a large quantity or amount. We use "much" with uncountable nouns (e.g., much water, much time) and "many" with countable nouns (e.g., many books, many apples). "Much" and "many" are used to ask questions (e.g., How much milk do you need? How many friends do you have?) and to make negative statements (e.g., There isn't much sugar left. I don't have many pencils). They help us specify the quantity of something in a clear and accurate way.