login/min_password_lng is a SAP Parameter attribute which is used to control Minimum Password Length 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 specifies the minimum length of the logon password. The
password must have at least three characters, however the administrator
can specify a greater minimum length. This setting applies when new
passwords are assigned and when existing passwords are changed or reset.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.