。
She is very generous with her money.
Literal
She [topic-は] very generously money [object-を] puts-out.
気前よく is the adverbial form of 気前がいい ('generous'), produced by replacing the final い with く on the いい portion. お金を出す ('put out money') is the standard idiom for 'spend money' or 'pay,' particularly with a flavor of contributing or footing the bill rather than buying for oneself. The whole sentence reads like an observation about a habitual trait.