Here the only information in the name is 2SJ525, a Japanese-standard part code where 2SJ marks a P-channel field-effect transistor. The 143 KB PDF is filed under schematics, yet it is probably the component datasheet. Any PDF reader opens it. Typical uses include confirming the gate, drain and source layout, reading maximum drain current and voltage, and checking switching parameters before replacing a failed device in a power or audio stage. Verify the exact marking and package before trusting the substitution.
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.