Filed as a schematic, the 112 KB document 2SC5046 is really labelled with a Japanese NPN transistor part number, which suggests a single-component datasheet. No further information such as manufacturer or package can be taken from the name. When servicing a board, this kind of sheet tells you which leg is which, the voltage and current limits and typical gain, so you can test the part and choose a substitute with equal or better ratings. Any PDF reader opens it.
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.