Boardview for the MSI MS-7B79 motherboard, revision 4.0, packed in a RAR archive. MSI uses MS numbers to identify its board designs, and the revision printed on the PCB must match for part locations to line up. Inside you should find a layout file that opens in boardview software such as OpenBoardView or FlexBV. It shows component positions, nets and test points for tracing power rails, checking shorts and locating parts without a full schematic.
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 @BoardSchematic. 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.
7-ZipWinRARThe Unarchiver (macOS)