Named 2SC5637, this 42.7 KB PDF is listed as a schematic but is presumably the datasheet for that transistor. In the Japanese JIS standard, the 2SC prefix denotes an NPN bipolar transistor, historically the high-frequency class. The name gives no manufacturer, package or revision. Technicians rely on such a sheet to read the pin layout, maximum voltage and current, gain and package outline when testing or replacing the part. Confirm the code printed on the component, since neighbouring numbers may differ.
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.