When customer present a gift card at the store to be redeemed you can do son on the tablet by going to the Gift Card tab.
Enter or Scan Gift Card QR Code
You can enter customer's gift card code which would look something like HPGC-D-ABC123. Once the pattern is matched the gift card balance will appear.
Redeem Gift Card
Tap redeem gift card and enter redeem amount to subtract the amount from the balance