Welcome to Android Central! What exactly are you trying to do? Do you mean that you want to be able to pay for things in the Play Store using payment options stored in your Google Wallet? BTW, Google Wallet doesn't exist any more -- it was rebranded/merged into Google Pay.
Or are you trying to transfer your Google Play credits so that you can use them to pay for other things? That's not possible -- Google Play credit is only for the Play Store.