Small zip archive for the ASUS X751SA laptop, with no document type, board revision or contents stated in the name. At 169 KB it is too small for a full BIOS image and is more likely a boardview or a short document, so open it to see what it contains. Whatever it holds, compare the board revision printed on the PCB with the files inside before using them for diagnosis, part location or flashing, since ASUS often makes several revisions of one model.
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 @boardviews. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip