Nokia Asha 309 material compressed as a 923 KB RAR archive. The name gives neither an RM type code nor the document type, so open it with WinRAR or 7-Zip to see what is included; small packages like this usually carry schematics or layout pages. These are used to trace the battery and charging path, find components on the board, measure voltages at test points and diagnose touch, display or no-power faults. Check the RM code on the label under the battery to make sure the variant matches.
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 @esquematicosparatodos. 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.