。
She did the work easily.
Literal
She [topic-は] easily that work [object-を] did.
した here is the past tense of the everyday する ('to do') — bare and noncommittal. する just says the action happened, with no claim about completion: whether the work was finished or merely undertaken is left open. If completion were the point, Japanese would reach for 終える ('finish'). Which verb maps to the English 'do' depends heavily on what's being done — work pairs with する here but やる, こなす, or 片付ける would each color the action differently (more casual, more skillful, more 'getting it out of the way'). 簡単に as the adverb softens it further: she did it without struggle, regardless of whether the result is final.