1. This sentence means: I am from the Chinese department. Or we could say 我是中文系的(学生), which is better to understand. 2. 回 means 回复， but we would rather say 会我个电话 instead of 回复我个电话. 3. When A looks for B, but B is not here and C is here, then C would ask A 你找A有什么事？It means: what do you want? If you like, I can take a message for B. What you've reffered is not a word to word translation, so you cannot take "message" as "事" directly.

1. "Here is the Chinese department" means “这里是中文系”。不知你这的“系”是指一个地方，还是专业？ 2.“回个电话”means “call me back”，回=back,举例：回家。 3.this sentence“你找他有什么事” doesn't always imply "Can I take a message".It depends.