Dawn; daybreak — the time when night ends and daylight begins (often seen in compounds like '夜明け' or '明け方').
夜明け前に家を出て、海辺まで歩いた。
I left home before dawn and walked to the seaside.
明け方になると鳥が一斉に鳴き始めた。
At daybreak the birds all began to sing at once.
夜が明けると気温が下がった。
When dawn came the temperature dropped.
The end of a period or event; soon after something has finished (often used as a suffix, e.g. '休み明け').
長い休暇明けで、会社は慌ただしかった。
The company was busy right after the long holiday break.
入院明けは無理をしないで安静にしてください。
After leaving the hospital, please don't overdo things and rest.
The beginning of a new year, month, etc.; as in '年明け' — the start of the year.
年明けに友人と一緒に初詣に行った。
At the start of the year I went to the first shrine visit with friends.
月明けは予算の調整で忙しくなる。
At the start of the month it's busy adjusting the budget.