Boardview packed in a RAR archive for the Dell Inspiron 3521 motherboard, Compal LA-9104P, in CAD format according to the name. A boardview shows component placement, part designators and net connections on both sides of the PCB, letting you locate test points and follow a signal from one part to another. CAD boardview files open in tools such as OpenBoardView, FlexBV or Boardviewer. The LA-xxxxP pattern is Compal numbering; check the revision printed on your board before trusting part positions.
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 @ITHINKHS. 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.