you can use it to buy things on eBay or any other business that accepts PayPal.
You can transfer the balance to a bank account.
You can use the 'Send money' feature to send the money to someone else's PayPal account.
If the refund was via a PayPal dispute it is normally returned to the original funding source. e.g. if the PayPal payment was funded by credit card then PayPal refund it to your credit card.