"后天"的英文表达是 "the day after tomorrow"。
其中"tomorrow" 是"明天"的意思， "after"是 "后"的意思，所以"the day after tomorrow"就是 "后天"。
例句：
I will see you the day after tomorrow. (我后天见你)
The meeting is scheduled for the day after tomorrow. (会议安排在后天举行)
I will finish my work the day after tomorrow. (我将在后天完成我的工作)