"V~기 전에" means some action before 'V' "초등학교 가기 전에 읽는 책입니다" can be broken into 2 parts. 1) 초등학교 가기 전에 읽 - Read before going to elementary school 2) 책입니다 - It is a book. and 1st part is describing 2nd with 는 so the sentence means "A book to read before going to an elementary school" is not literal but really close :D "~기 전에" is a combination of 2 things: 1) ~기 turns a verb into a noun. 2) 전에 is a time word with a meaning of "before" Of course it can be used with nouns since 기 is there to turn Verb into a Noun so if its orignally a noun to begin with you dont need it. example: "이야기 (Talk, Story) 전에" -> "Before the talk/story" The opposite of this is "~(으)ㄴ 후에" if you were wondering which means "After" but I won't go into it. instead read this lesson if you want to know more https://www.howtostudykorean.com/unit1/unit-1-lessons-17-25-2/lesson-24/ Hope I helped