Compact archive referring to the NE5558 / SA4558 family part numbering, most likely a datasheet for a 4558-type dual operational amplifier. At 42.4 KB it probably contains a single PDF with the pinout, electrical characteristics and typical application circuits. Technicians use such sheets to identify pins, check supply limits and confirm a substitute part when repairing audio stages and similar analogue circuits. Confirm the suffix and package markings on the actual chip against the datasheet before replacing it, as variants differ.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @IT_SERVICE_WORLD. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.