Archive named A510FD, the model code of the Samsung Galaxy A5 (2016) dual-SIM phone, SM-A510FD. The name gives no further detail, so the contents must be checked after extraction. At 1.54 MB it more likely holds schematics or repair guides than full firmware. Such documents help trace power rails, locate test points and diagnose charging or no-power faults. Make sure the hardware revision of the phone matches before relying on the data.
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 @mobile_jump2. 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.
7-ZipWinRARThe Unarchiver (macOS)