RAR archive of roughly 7.2 MB named for the Dell G7 7588 gaming laptop, with a (3) suffix suggesting it is one of several copies or variants. The name does not reveal what is inside, so open it to see whether it carries a BIOS dump, boardview or schematic. If a firmware image is included, it would be flashed to the SPI chip with a programmer after backing up the original. Always match the board number and revision on the PCB with any documentation before using it.
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 @laptopbios21. 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.
7-ZipWinRARThe Unarchiver (macOS)