。
She is a very kind girl.
Literal
She [topic-は] very kind girl is.
親切 is a na-adjective, so it needs な before a noun (親切な少女). 少女 is the literary or formal word for 'girl,' more common in fiction, news, and titles than the conversational 女の子 — think 少女漫画 (girls' manga), 美少女 (beautiful young girl in anime/manga register).