。
Her hat got blown off by a strong wind.
Literal
She [topic-は] strong wind [by-で] hat [object-を] was-blown-away.
This is the indirect or 'adversative' passive — a uniquely Japanese construction where the topic (彼女) is presented not as the agent or the patient of the action but as the *affected party*. Literally, the wind blew the hat away, and *she* suffered for it. Most European languages can't render this without rephrasing ('she had her hat blown off' or 'her hat got blown off') because the topic isn't the syntactic subject of any of the events involved. The で on 強い風 marks the cause (something happens because of the wind), distinct from the instrumental で you'd see in 鉛筆で書く ('write with a pencil'). 吹き飛ばす itself is a compound: 吹く ('blow') stacked with 飛ばす ('send flying'), giving the gust a clear trajectory through the air.