For the New Year to begin; to turn into the new year (commonly used to describe the start of the year).
年が明けると町は一気にお正月ムードになる。
When the new year begins, the town quickly takes on a New Year's atmosphere.
年が明けたら、まず初詣に行くつもりだ。
When the new year comes, I plan to go to the first shrine visit of the year.
年が明けると心機一転、新しい目標を立てる人が多い。
When the year begins, many people set new goals for a fresh start.