Hi Ms. latifa, I'm afraid that Nanhai is not a city since it is just a district of Foshan City of Guangdong. And, there is no train between them. So, you have to get on a bus. Now, the Fangcun Passenger Station of GUangzhou has continual buses to Foshan most of which stop at Nanhai Bus Station. It takes no more than a half hour and 10yuan.