RAR archive of 331 KB labelled R33-MB-B, which reads as a motherboard code R33 with revision B, though the name does not say which laptop or which kind of document is inside. Given the small size it most likely holds a boardview or a compact schematic set, but extract it and check the contents before relying on it. Technicians use such packages to trace power rails, find components and test points, and chase shorts. Compare the code and revision silkscreened on the PCB with the archive label before using any measurements from 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 @cyberlanelectonik. 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.