Boardview for a mainboard labelled NB2608, marked MB V4, packed into a 7.95 MB rar archive. The name states no brand, maker or laptop model, only the board code and what appears to be version 4, so check the markings on your PCB carefully before use. A boardview shows component placement and net connections on both sides of the board. It lets you locate parts, test points and connectors, follow power rails and narrow down shorts. Open it in a viewer such as OpenBoardView or FlexBV, depending on the format inside.
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 @BoardSchematic. 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.