Lock and unlock the mobile phone card. What does Unicom mean by sending back a short message "password reset random code"?

"The password of the mobile phone SIM card is initially set to 1234. If the error code is entered three times in a row, the card will be locked. At this time, you need to enter the PUK password to unlock it. However, after entering the error code 10 times, the SIM card cannot be recovered. You can log in to Unicom's online business hall, click the villain icon in the upper left corner after entering, and your PUK code information will be displayed. You can also log in to the mobile phone business hall or contact the local manual service for inquiry. " "Password reset random code" means that when you send an instruction to reset the service password, Unicom will send you a random code to verify your identity. "