"Many" is the intensifier for nouns, "very* is the intensifier for adjectives. The Korean here has an intensifier, "okd" is an adjective, and Duolingo makes us used to literal translations, but here we must use free translation and are marked wrong for literally translating the intensifier.
Sometimes in Korean people refer to family members as our when they are talking to other people, espeacially when they are close to that person whom is they are talking to. Also, some Koreans like to think family don't belong to them. Research this if you are confused. I am not an expert on Korean culture.