
peace of mind; relief; (sense of) security; safety; assurance; confidence
「安心」 has another reading with different meanings.
試験に受かって安心した。
I was relieved to pass the exam.
試験が終わって、やっと安心しました。
The exam is over, and I finally feel relieved.
母から無事だと連絡が来て安心した。
I felt relieved when my mother called to say she was safe.