A small 28.6 KB PDF, catalogued as a schematic, referenced by the transistor number 2SC2812N. The 2SC prefix follows the JIS convention for NPN bipolar transistors, and the trailing N is part of the name; its meaning is not stated here. A file this size is typically a short datasheet page. Read it for pin assignment, package outline and absolute maximum ratings when hunting a substitute part. Compare the body marking and any suffix letters on the component before trusting the match.
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.