Samsung Galaxy J4 repair archive for model J400F, an 11.8 MB RAR file. Its contents are not stated in the name, but a package of this size likely holds schematic pages and service documentation for the handset. Technicians use this material to follow the battery and charging paths, check for shorts on main supply lines and identify connectors and test points. Extract it with WinRAR or 7-Zip, and compare the model code on the device with J400F before applying measurements or part references from the documents.
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 @esquematicosdecelulares. 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.