。
She quickly brushed off my shoes for me.
Literal
She [topic-は] my shoes [to-に] quickly brush [object-を] applied [for-me-くれた].
ブラシをかける ('to apply a brush, to brush something') uses the catch-all verb かける ('apply, hang, pour, put on') — Japanese uses かける for an enormous range of actions involving applying or directing one thing onto another. The に marks the shoes as the target of the brushing. さっと is a 擬態語 mimetic capturing a quick, light, deft action — 'with a swift, light motion.' Pairing さっと with かけてくれた and the loanword ブラシ keeps the sentence brisk and slightly cinematic — a small, considerate gesture rendered in compact prose.