To happen to meet or come across someone or something; to run into; to encounter (by chance).
駅で昔のクラスメートに出くわした。
I ran into an old classmate at the station.
旅行中に珍しい動物に出くわして驚いた。
I was surprised to come across a rare animal while traveling.
トラブルに出くわしたら、すぐに上司に報告してください。
If you encounter trouble, report it to your supervisor immediately.