The part number 2SC4473 is the only information in this 122 KB PDF name, and it identifies a Japanese JIS-coded NPN transistor of the high-frequency type. Although indexed as a schematic, the document is most likely the component datasheet. It can be opened in any PDF viewer to read the package drawing, pinout, maximum ratings and characteristic curves, which help when diagnosing a shorted or open transistor and when judging whether a cross-reference part offers adequate voltage, current and frequency margins.
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.