。
Not only English — she can speak French as well.
Literal
She [topic-は] English [only-だけ] [is-not-でなく] French [also-も] talk thing can-do.
しゃべる ('to chat / talk') is a colloquial cousin of 話す. While 話す is neutral and works in any register, しゃべる leans casual — it suggests informal chatting, talkativeness, or gossipy conversation, and is sometimes mildly negative ('shooting one's mouth off'). Pairing it with the formal ~ことができます creates a slight register clash that's actually common in everyday speech: people often blend casual verbs with polite endings to sound friendly without going fully informal.