Gift card adds 30 AUD to your AppStore account. You may use it only on AU (Australia) accounts.
No expiration date.
There seems to be a difference between the available Store Credit of yours with the site currency you had picked previously. Would you like to:
PlayStation Network(PSN) Gift Cards USD $56.1
Software & Apps Software & Apps USD $25.95
Honkai: Star Rail Top up USD $23.65
NHL 26 Video Games USD $68.99
Dying Light: The Beast Video Games USD $52.79
Plants vs. Zombies: Replanted Video Games USD $24.99
F1 25 Video Games USD $76.49
Genshin Impact Top up USD $69.96