Dear teachers:

She is all out of change.

What does it mean?

Please advise. Many thanks.

Change refers to small amounts of money, usually coins (as opposed to paper money).
The woman referred to is likely someone who works as a cashier.
People buy things. They pay her in large amounts. She returns their change.
If her cash register has no more money (especially coins) that she can use as change, then she is all out of change.

When you are "all out of" something, it means you have no more of it.
If your car is all out of gas, you can't drive it.

Silly me. I forgot "change" also means money. Thanks for reminding.