"qryff" is a command that runs on the IBM iSeries (or AS400). It allows you to run SQL queries on the OS400 database from the command line or a CL program. You can output information to the screen, print, or a file. You can also update, delete, insert, and whatever else the iSeries query engine supports.
Technically, it is simply an interface to the operating system's "Start Query Management Query (STRQMQRY)" command. I wrote this back in the 1990's and it's been freeware since.