This is the 1605th most frequent Korean word.
무거운
Heavy.
The word '무거운' is used as an adjective to describe the nature of the items in the bag as being heavy.
이 가방은 무거운 물건들로 가득 차 있어요.
This bag is full of heavy items.
Here, '무거운' is used metaphorically to describe the topic as being serious or grave in nature.
오늘은 무거운 주제를 토론하기로 했습니다.
Today we decided to discuss a serious topic.
In this sentence, '무거운' describes '짐' (load) as being physically heavy.