Can you help me understand this C Programming question?

you will write a C function generateDefaultPassword(char* default_password, const char* username) that generates a default password randomly, which will be sent to the user to login. The users may wish to change the default password to a password of their own, which should pass the password strength meter you implemented in Part I. The default password generated by this function will be stored in a char array that the default_password is pointing to. Remember, the caller of this function (aka main()) must declare an array before passing it to this function, in order to avoid segmentation fault issues.