When are the pronouns Y and EN used?

Starting with the pronoun "y". "Y" is used to replace the repetition of a place, that has been introduced in a sentence by a proposition such as "à", "dans", "chez", "en", which mean respectively "in"/"to", "in", "in someone's house". "Y" can be translated as "there" in English.Some examples to demonstrate this:·       Est- que tu habites à Madrid? (Do you live in Madrid?)To avoid repeating "à Madrid" ("in Madrid"), we say "Oui, j'y habite." or "Non, j'y habite pas." (Yes, I live there/ No, I do not live there.)"J'y" because two vowels can't be next to each other in a sentence, therefore they are merged with an apostrophe.·       Marie est allée chez Pierre. (Marie went to Pierre's house.)En utilisant le pronom "y": Marie est y allée. (Marie went there.) ·       Ma mère va aller dans le magasin. (My mom will go to the shop.)Ma mère va y aller. (My mom will go there.)
“Y” is also used to replace “à+ something” e.g. s’intéresser à quelque chose, penser à quelque chose, etc.Examples:·       Pensez- vous à votre travail ?  (Do you think about your job?)Non, on n’y pense pas. (No, we don’t think about it.)·       Tu t’intéresses au cinéma ? Oui, je m’y intéresse.
“En” is a pronoun that replaces “de+ noun”. “En” always comes BEFORE the verb.Examples: ·       As-tu des pommes ? (Do you have apples ?)Oui, j’en ai un peu. (Yes, I have some.)·       J’ai besoin de repose. J’en ai besoin. (I need a break. I need it.)·       Elle rêve des étoiles cette nuit. Elle en rêvait la nuit dernière aussi.(She dreams of stars tonight. She dreamt of them last night too.)