RAR archive labelled only with the Dell M5110 model name, with no board number, ODM, revision or contents stated. At about 1.6 MB it probably holds a schematic or boardview for that laptop, but this must be verified after extraction. Repair documents like this help in tracing power rails, finding test points and isolating shorts on the mainboard. Since the board number is missing from the name, compare the number printed on your PCB with the one inside the documents before relying on them.
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 @IT_SERVICE_WORLD. 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.