the period or day immediately after a series of consecutive holidays; when work or school resumes after a long weekend/holiday stretch.
連休明けの月曜日はいつも仕事が忙しい。
Mondays after a long holiday are always busy at work.
連休明けで学校の宿題が山ほど出た。
After the holidays, the school gave a ton of homework.
旅行から帰ってきて連休明けに出社したらメールが山積みだった。
I returned from a trip and when I went to the office after the holidays, my inbox was full.