RAR archive of 949 KB tied to the MSI-style board number MS-7046, with an M1 suffix that most likely marks a sub-variant or revision of that desktop motherboard. The name does not say what is inside, but archives of this size usually hold a schematic set in PDF form. Technicians use such material to trace power rails, follow signals between chipset and slots, and find test points when diagnosing a dead or shorted board. Before relying on it, compare the MS number and revision silkscreened on the PCB with the one in the documents.
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.