You can simply say it '책 상자' for a box of books. e.g. 와인 상자 = a box of wine bottles 사과 상자 = a box of apples 라면 상자 = a box of ramen (usually instant ramen noodles) * I assume you want to say "I cannot lift this box of books because it's very heavy." Then I would say, "이 책 상자가 아주 무거워서 들 수가 없어요."

Also instead of 상자, I'd say that the word "박스 (pronounced more like 빡스)" is used just as often in Korean