Have you ever seen a machine where you can get cash out from your bank account? That's called an ATM (automated teller machine). When you use an ATM to withdraw money, the bank charges you a fee for the service. This is called an ATM usage fee.
The bank wants you to use their machines to get the money, as it costs them money to maintain and operate the machines. To cover those costs and make a profit, they charge you a fee for the service.
The fee varies from one ATM to another, and it can be different for different types of accounts or bank cards. Sometimes, your own bank won't charge you a fee when you use their ATMs, but if you use an ATM from a different bank, they may charge you a fee. This is because your bank has to pay a fee themselves to the bank that owns the ATM you used.
ATM usage fees can add up quickly, so it's important to pay attention to how much you're being charged. Some banks offer fee-free ATM networks or refunding fees, so be sure to check with your bank and plan accordingly.