RAR archive of 1.72 MB labelled only for the Xiaomi Redmi Note 8 Pro, written as Mi note 8 pro; the name does not say what is inside. Given its size it most likely holds service documentation such as a schematic or board layout rather than firmware, but that should be verified after extraction with WinRAR or 7-Zip. If it contains diagrams, they can be used to trace power rails, locate test points and identify components near a short. Check that the board revision printed on the PCB matches anything documented 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 @cyberlanelectonik. 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.