The 232 KB PDF covers the 2SD1947A, a JIS NPN transistor number with an A suffix that the name states. The suffix typically marks a variant of the base type, so it should not be swapped blindly with the plain 2SD1947. The index labels it a schematic, but the content should be a part datasheet. Read the ratings tables and package drawing before choosing a replacement, and confirm the suffix letter printed on the original component. The datasheet is also handy for checking hFE class and safe operating limits.
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.