Quantity refers to the amount or number of something. In English, we use words like "some," "many," "a few," and "a lot of" to express quantity. We also use quantifiers like "much," "a little," and "few" to show how much or how many of something there is. Understanding quantity is important for clear communication and to provide specific information about amounts. For example, "I have some books" gives a general idea of the amount, while "I have 20 books" gives a specific quantity.