backproc/steplevel_db_write is a SAP Parameter attribute which is used to control background processing: db-write for each step vs end-of-job 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 .
on: (default) for each step
off: a db write only at end-of-job for all the steps (at once)
See SAP Parameter Documentation for full SAP documentation for this profile parameter.