How to use the money on my Apple Cash card?

There are a number of options:

Transfer it to a bank or debit card: Transfer money in Apple Cash to your bank account or debit card - Apple Support

Use it to send money to someone else: Send and receive money with Apple Cash - Apple Support

Use it to buy something somewhere that Apple Pay is accepted: Make purchases using Apple Pay - Apple Support

Use it to make a payment on your Apple Card balance due (if you have an Apple Card): How to make Apple Card payments - Apple Support