All SIM cards are protected with a PIN number. The PIN (Personal Identification Number) is provided to you at the back of your SIM Card holder when you purchase the sim card. Standard PIN codes are 4 digits in length. If you forget your PIN, or enter the pin incorrectly 3 times, then the second security measure known as the PUK code is enabled. The PIN and PUK codes can be found on the SIM card holder that is provided to you when the sim was purchased. There is a PUK 1 and PUK 2 code to help with securing your SIM pin. You can use it to unlock a blocked SIM pin.
How to access SIM PIN & PUK
At the back of your sim card holder shown in red box is your PUK and the PIN by it
Ensure to keep your sim card holder in a safe place as it is usually used for verification processes