passcode iphone 8

If you bought a phone and it's asking for a passcode, then you didn't buy an unlocked one. When you first power it up, you should get the Hello screen. If you don't see that, return it for a refund.

Ask your mom to unlock the iPhone with her passcode, If she forgot her passcode ask her to see this Apple article: If you forgot your iPhone passcode

https://support.apple.com/en-us/HT204306

Unlock Passcode -> without a computer.

How to reset your iPhone, iPad, or iPod touch when you forgot your passcode

https://support.apple.com/en-us/HT212951