。
She usually doesn't eat much.
Literal
She [topic-は] usually much thing [object-を] doesn't-eat.
あまり~ない is a paired construction where the adverb あまり ('much, very') only carries that meaning under negation — the verb has to be negative for the phrase to mean 'not very, not much.' Without the negation, あまり means 'too much, excessively,' which is a different beast. ふつう ('normally, usually') sets up a habitual frame — what she does as a rule. もの ('thing') here is broader than 'food'; the sentence describes a general eating habit rather than a single meal.