DIR_SERVER_ORAHOME is a SAP Parameter attribute which is used to control Root-path of ORACLE software on the database server 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 .
The specified parameter value must contain the name of the directory in
which the Oracle database software is installed on the database server.
With an R/3 standard installation this is /oracle/<(><<)>SID>.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.