Apple logic board 820-2914 is the only detail stated for this 2.40 MB zip archive; the model and revision are not mentioned. Apple numbers its logic boards with the 820 prefix, so the package probably holds a schematic, a boardview or both. They help with mapping the power path, measuring rails, finding test points and isolating a short circuit on the board. Extract and open the PDF in any reader and layout files in OpenBoardView, and verify the board marking and revision letter first.
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 @notebookschematic. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.