This is the 31st most frequent Japanese word.
ため
"ため" means "sake," "purpose," "benefit," or "reason" depending on context.
In this sentence, 'ため' signifies doing something 'for' someone, in this case, 'for him'.
彼のために料理を作りました。
I cooked a meal for him.
Here, 'ため' expresses the purpose of the action, describing the reason 'for' doing the activity, 'for health'.
健康のために毎日運動します。
I exercise every day for my health.
In this instance, 'ため' is used to denote the cause or reason something is happening, 'due to the accident' in this context.