Happiness, blessedness, or good fortune (a state of being fortunate).
あなたの無事が何よりの幸いです。
Your safety is the greatest happiness (above all).
家族が元気でいることが彼の幸いだ。
His happiness is that his family is healthy.
小さな親切が大きな幸いをもたらした。
A small kindness brought great good fortune.
Luckily; fortunately — used adverbially to indicate something happened to good effect.
幸い、会議は予定より早く終わった。
Fortunately, the meeting ended earlier than scheduled.
幸いにも彼が近くにいて助かった。
Fortunately, he was nearby and helped.
交通事故にならず、幸いでした。
It was fortunate that there was no traffic accident.