This 125 KB PDF refers to 2SC5066FT, an NPN transistor in the Japanese 2SC numbering; the FT suffix most likely denotes a package or variant code, which the document itself should define. Although typed as a schematic, the content is presumably a part datasheet. Compare it with the larger 2SC5066 file if both exist. Use it to confirm the exact package footprint, pinout and ratings, because suffix variants of one transistor can differ in outline and pin order.
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.