Security code

I have never heard of a security code being involved.

This article explains the different kinds of gift cards Apple uses and has links on how to redeem them and what can be purchased with each kind. Click on the link --> What type of gift card do I have? - https://support.apple.com/HT204199

I also am wondering about that web site at the bottom. Apple tends to use sites on its own apple.com or icloud.com domains.

Those make me suspicious about the card.