I asked her to talk to him, but she wouldn't.

wouldn't 是 would not 的缩写形式，would 是情态动词，表示"愿意"或"将要"的意思，加上否定词 not 表示"不愿意"或"拒绝"。 在这个句子中，wouldn't 表示"不愿意"的意思，强调她拒绝和对方谈话的态度。