Indexed as a schematic, this 59 KB PDF carries the name 2SC4655 with an E suffix, which plausibly denotes an English-language version. 2SC identifies an NPN bipolar transistor under Japanese JIS numbering, so the content is likely a component datasheet. Expect maximum ratings, hFE classification, frequency characteristics and a package diagram. Technicians use such a sheet to verify pins, to match a replacement by voltage, current and gain, and to decode the small SMD marking printed on the part.
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.