This is the 19581st most frequent Korean word.
어려워서
"Because (it is) difficult."
In this sentence, '어려워서' is used to indicate that the difficulty of the problem leads to the consequence of it being hard to solve.
그 문제는 어려워서 풀기가 힘듭니다.
The problem is difficult, so it's hard to solve.
Here, '어려워서' indicates the reason why the speaker needs to dedicate much effort to studying, contextualizing the cause-effect relationship.
한국어가 어려워서 공부를 많이 해야 해요.
Korean is difficult, so you have to study a lot.
In this case, '어려워서' is used to explain the causal factor for the time delay, illustrating the result of the complexity of the route.