Take care; be careful — an expression telling someone to act safely or pay attention (often used as a farewell or warning).
行ってらっしゃい。気を付けてね。
Have a good trip. Take care.
夜道は暗いから、足元に気を付けて歩いてください。
The streets are dark at night, so watch your step as you walk.
海外出張、気を付けて行ってきてください。
Take care on your business trip abroad.