noun
Financial protection against loss, illness, accidents, etc. Used in compounds like 生命保険 (life insurance) and 自動車保険 (car insurance).
海外旅行に行く前に保険に入った。
I took out insurance before going on an overseas trip.
この病院は保険がきく
This hospital accepts insurance.
noun
guarantee; warranty; safeguard
A promise or measure that ensures something will happen or be protected; often used figuratively. Common in phrases like 保険をかける (to take precautions) or 保険の意味で (as a safeguard).
合格するために、もう一つ大学を受けるのは保険だ。
Applying to one more university is a safeguard in case I don't pass.
データのバックアップは一種の保険です。
Backing up data is a kind of insurance.