After Kaiping I will be going to Sanya. Do you know which bus/train I can get?

No direct train runs for this journey. The direct long-distance bus has just stopped operating and the resume news has not been published yet. In this case, I have two pieces of advice for you.

First, at the local bus station, you can easily catch a bus to Zhaoqing in around 2h. Upon arrival at Zhaoqing, you can trasnfer to take a train to Sanya directly. However, only one train runs from Zhaoqing to Sanya every day, departing at 16:55.

Second, you can take the long-distance bus to Haikou first. Only one such bus is in service every day, departing at 19:00. After around 12h's journey, you will arrive at Haikou, where you can easily catch a direct bus to Sanya.

You do know Kaiping ciy is on the mainland and Sanya and Haikou is on Hainan island. Thus you probably needto get to a bigger city and fly or bus to a port city where you take a ferry to Haikou. I doubt there's ferry to Sanya.