This is the 5200th most frequent Korean word.
다음날인
"The next day."
Here, "다음날인" introduces Tuesday as the subsequent day in the timeline.
다음날인 화요일에 우리는 그 장소를 방문했어요.
On Tuesday, the next day, we visited that place.
"다음날인" is used in this context to link Wednesday to being the subsequent day in conversation.
다음날인 수요일엔 비가 올 예정이랍니다.
On Wednesday, the next day, it's expected to rain.
In this sentence, "다음날인" is used to specify that the referenced day (Monday) is the next day.