RAR archive, 809 KB, with documentation for the MSI MS-1251 mainboard; no model name or revision is stated. MS-12xx is MSI own numbering for its notebook boards. The package most likely holds a schematic used to trace power rails, follow the charging and power-on path, and find components when a laptop is dead or shorted. Open it with an archive tool and a PDF or schematic viewer, then confirm that the board number and revision on the PCB match before using component values or test points 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 @generalschematics. 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.