。
She did a lot of work.
Literal
She [topic-は] a-lot work [object-を] did.
たくさん is the everyday adverbial 'a lot, many, lots of' — it can directly modify a verb (たくさん食べる 'eat a lot') or a noun (たくさんの本 'lots of books'). Here it's adverbial: 'worked a lot.' Note the choice of 仕事 (shigoto) over the verbal form 働く (hataraku); using 仕事をする ('do work') treats the work as a quantifiable thing to be tackled in chunks, fitting たくさん more naturally than the activity verb 働く (which would more naturally take an adverb of duration like ずっと or 一生懸命).