The name refers to the 2SC5502, a part in the Japanese 2SC numbering family reserved for NPN bipolar transistors. The PDF is 48.1 KB and is filed under schematics, but at that size it is most likely a manufacturer datasheet. Such a sheet normally gives pin assignment, package drawing, maximum ratings, gain and switching data. Use it to pick a suitable substitute, verify that the marking on the part matches, and confirm the pin order before soldering, because pinouts differ between packages.
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.