RAR archive of 268 KB for the ASUS X550WE motherboard, revision 2.0. The name does not say what is inside, but at this size it most likely holds service documentation such as a schematic or boardview rather than a full BIOS image, so check the contents after extracting. Technicians use such material to trace power rails, find components and test points, and follow signals while diagnosing shorts or no-power faults. Make sure the board revision silkscreened on the PCB matches 2.0 before relying on it.
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 @schematicslaptop. 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.