spnego/enable is a SAP Parameter attribute which is used to control Enable SPNego Module 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 .
If this parameter is set to "1", the work process will attempt to load
the Kerberos/SPNego library from the file location determined by profile
parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.