During Checkout on eBay.com:
Enter the 13-digit redemption code, then click Apply.
Review the payment details and click Confirm and Pay.
In-Store Mobile redemption instructions:
To redeem your eGift Card from a mobile device, display the barcode or gift card number and associated PIN (if applicable) to the cashier at the time of purchase.
Note: It can take up to 4 hours for your eBay Gift Card to be activated and ready to be redeemed.