RAR archive of roughly 7.9 MB for the Samsung Galaxy A12, model SM-A125F. The name gives no information about what is included, though packages of this kind usually contain schematic or board layout documents. A technician relies on them to trace power rails, locate charging ICs and connectors, and identify test points while diagnosing no-power or no-charge faults. Extract it with WinRAR or 7-Zip and check that the model code on the device matches, as other A12 variants use different boards.
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 @esquemaseletricos. 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.