This is the 7711th most frequent Korean word.
풀린
"풀린" means "loosened" or "released."
In this sentence, '풀린' describes the state of the knot having been untied.
얽혀 있던 매듭이 풀린 후에 줄이 길게 늘어졌다.
After the tangled knot was untied, the rope stretched long.
Here, '풀린' conveys the idea of a situation or problem being solved or resolved.
그의 오랜 고민이 드디어 풀린 느낌이다.
It feels like his long-held worries have finally been resolved.
In this context, '풀린' expresses the relieving or loosening of tension or stress.