This is the 12549th most frequent Korean word.
대만에선
"In Taiwan."
The word '대만에선' sets the context of location in Taiwan for the subject of the sentence.
대만에선 음식이 맛있어요.
In Taiwan, the food is delicious.
Here, '대만에선' introduces the location, Taiwan, emphasizing where public transportation is being discussed.
대만에선 대중교통이 편리합니다.
In Taiwan, public transportation is convenient.
In this sentence, '대만에선' provides the locative context to introduce Taiwan as the place where this cultural observation applies.