This is the 18232nd most frequent Korean word.
숲을
"숲을" means "forest" in the accusative case (receiving the action).
In this sentence, '숲을' is used as the object of the verb '걸어다니며' (walking through). It means the forest is the area being traversed.
나는 숲을 걸어다니며 자연을 느꼈다.
I walked through the forest feeling the nature.
Here, '숲을' acts as the object of the verb '보호하는' (protecting). It emphasizes the forest as the entity to be preserved.
숲을 보호하는 것이 매우 중요합니다.
Protecting the forest is very important.
In this usage, '숲을' serves as the object of the verb '탐험했습니다' (explored), indicating that the forest is the subject of exploration.