RAR archive of about 216 KB named after a board code Y0B-MB-B; the name does not say whether it holds a schematic, boardview or firmware. The small size is typical of a compressed boardview file, though the contents should be checked after extraction. If it contains a layout, open it in a boardview program to locate components, follow nets and find test points. If it is a firmware image, compare its size with the flash chip and back up the original before writing. Make sure the PCB code, including the B suffix, matches.
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.