A euphemistic expression meaning 'to die' or 'to pass away'; a polite or softened way to say someone has died.
祖父が先週亡くなりました。葬儀は来週です。
My grandfather passed away last week. The funeral is next week.
ニュースでその俳優が亡くなったと知って驚いた。
I was surprised to learn from the news that that actor had passed away.
彼女は病気の母が亡くなったと聞いて、すぐに帰国した。
She heard that her sick mother had passed away and immediately returned home.