Does your friend actually live in Ireland? If not, the card cannot be used by your friend, nor will your friend find it easy to simply change the country settings to Ireland simply for the purpose of using that gift card. Gifts are country-specific. This version of the link will take you to the section of the support article about what to do if your code must be redeemed in a different country or region If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support
The support article Change your Apple Account country or region - Apple Support describes how to change your country setting on everything using your Apple Account, and the requirements and results of doing this. Changing store country is not a trivial endeavour. The system is designed to only facilitate doing this if you are moving to the other country to take up residency. It makes it difficult for people to temporarily change country settings to do things such as get around distribution restrictions only allowing them to buy items available in the country where they actually live.
Find somebody in Ireland who can use the gift. Check your Apple Account balance - Apple Support says:
"About unused Apple ID balance
You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards, or unused Apple ID balance for cash, except as required by law. If your jurisdiction allows for refund of redeemed gift balances, you can contact Apple Support [ Contact - Official Apple Support ] to request a refund."