This is a good way to ask for information from a bank teller, a store cashier, or a person you don't know.

You ask using an embedded question. So instead of asking, "What is my balance?" you ask:

Can you tell me what my balance is?

If you want to ask "Who is that?", you form the question this way:

Can you tell me who that is?

For more information on embedded questions, read here.