Part number 2SC4324 is the only information in the name of this 468 KB PDF, which is catalogued as a schematic but almost certainly holds the device datasheet. Following JIS conventions, 2SC marks an NPN bipolar transistor, typically printed as C4324 on the case. Technicians use such sheets to confirm which lead is base, collector and emitter, to read the absolute maximum ratings and characteristic curves, and to judge whether a substitute part is safe to fit after a failed transistor is found shorted.
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 .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.