Explain the use of the pronoun ‘en’ in French with examples?

The pronoun 'en' in French is used to replace a noun that follows the preposition 'de' (meaning 'of' or 'from') or a quantity of something. It can also mean 'some' or 'any' when used with a countable or uncountable noun. Examples: 1. J'ai besoin de deux pommes. (I need two apples.) -> J'en ai besoin. (I need them.) 2. Il parle de son travail. (He is talking about his work.) -> Il en parle. (He is talking about it.) 3. As-tu du lait ? (Do you have any milk?) -> Oui, j'en ai. (Yes, I have some.) 4. Il a achet? beaucoup de livres. (He bought a lot of books.) -> Il en a achet? beaucoup. (He bought a lot of them.)