Can you tell me (embedded question)

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.

(someone's) balance

The "balance" of a bank account is the amount of money that you have in the account. So your account balance is a number. For example:

Your balance is $2,154.

The action most commonly associated with a bank balance is "checking":

When's the last time you checked the balance?