RAR archive of 949 KB labelled N50A and N51A, model or project codes that likely refer to a shared notebook motherboard; the brand and board revision are not stated. The contents are probably schematics, used to trace power rails, locate components and test points and check shorts. Since the name is brief, extract the archive with WinRAR or 7-Zip and read the title block to confirm the exact model. Match the board code printed on the PCB before relying on any reference designators.
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 @generalschematics. 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.