Boardview for a main logic board, marked only as mlb with the project code j140; the name gives no board number, revision or brand. The .pcb file holds component placement and netlist data, so a viewer such as OpenBoardView or FlexBV can highlight a net across the board, show pin connections and help locate test points or a shorted part. Since the target hardware is not stated, open the file and compare the board outline and part markings with your PCB before relying on it for measurements.
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 @LaptopsBoardview. Enginerys does not host this file.
How to open a .pcb file
In repair archives a .pcb is typically an XZZ (XinZhiZao) boardview — popular for phones and recent laptops.