。
She passed away, leaving her son a large sum of money.
Literal
She [topic-は] son [to-に] large-sum-of [genitive-の] money [object-を] left-and passed-away.
亡くなる ('to pass away, die') is the standard polite/euphemistic verb for human death — softer and more respectful than 死ぬ. 残す ('leave behind') in the te-form 残して links the bequeathing with the dying — 'leaving X behind, [she] passed away.' に marks the recipient (the son), and を the thing left behind. The sequence te-form + 亡くなる is a familiar narrative shape for end-of-life summaries.