login/password_change_waittime is a SAP Parameter attribute which is used to control Password change possible after # days (since last change) information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter can be used to define the period of time (measured in days) after which a user can change his or her password again. Only password changes that the user has requested are taken into account. If the password is set to a new value by the administrator, the user can/must change the password the next time he or she logs on (with the exception of SERVICE/SYSTEM users). If the system forces the password change (for example, after the period defined using
See SAP Parameter Documentation for full SAP documentation for this profile parameter.