。
She put a lot of sugar in her coffee.
Literal
She [topic-は] coffee [into-に] lots-of sugar [object-を] put.
A clean putting-into-a-container template: 入れる ('put into') with the destination marked by に. Notable here is the word order: たくさん ('a lot') appears as a bare adverb before the object 砂糖 — Japanese can place quantity adverbs either right before the verb (砂糖をたくさん入れた) or before the object (たくさん砂糖を入れた), with subtle nuance differences. The fronted adverb here puts a little extra emphasis on the largeness of the amount.