Could you tell me what it is about please?

请告诉我，你有什么事情吗？

If anyone can tell me what it is I would be grateful.

如果有人能告诉这是什么，我将不胜感激。

In case he does not have your number, could you tell me what it is?

以防他没有你的电话号码，你能告诉我你的号码吗？