Compressed ZIP package, 464 KB, labelled N68S3B, a name that looks like a desktop board model code. Nothing in the name states the contents, so treat it as unidentified until unpacked; the small size suggests a firmware image or a compact document rather than a full boardview set. When it proves to be a BIOS file, verify that it fits the flash chip capacity, read and store the existing chip contents with a programmer, and make sure the board model printed on the PCB is the same.
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 @laptopchiplevelrepair. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.