。
She cut the leafy tops off the carrots.
Literal
She [topic-は] carrot [genitive-の] leaves [object-を] cut-off.
切り落とす is a compound verb 切る ('cut') + 落とす ('drop, cause to fall'), meaning 'to cut off, sever, lop off.' The 落とす component frames the cut as a complete severing — the cut-off piece falls away, no longer attached. Compare with 切り離す ('separate by cutting'), 切り取る ('cut out'), 切り捨てる ('cut and discard'). にんじんの葉 ('carrot leaves') refers to the green leafy tops on whole carrots, which are typically trimmed before sale or storage but are themselves edible (often used in tempura, stir-fry, or pesto in farmhouse cooking).