After top you iTunes account you can buy in App Store, iTunes Store and Mac App Store software, games, movies, music.
🔑Redeem and use iTunes Gift Cards:
1. Tap iTunes Store, App Store, or iBooks Store on your device.
2. Scroll to the bottom of the Featured section and tap Redeem. You will need to sign in with your Apple ID.
3. Tap "You can also enter your code manually."
4. Enter your gift code and tap Redeem
5. After you redeem a gift card code, your iTunes account balance will update. You might need to sign out and back in to all of your devices for your balance to appear. You can find your balance underneath your Apple ID.
Attention: You can only redeem this card to INDIA (INR) accounts!