This PDF of 71.0 KB is indexed as a schematic for the 2N6520, a JEDEC 2N-series discrete semiconductor number. The name gives no board or device, so the document is most likely a component datasheet with electrical characteristics, maximum ratings and the package pinout. Repair work uses such sheets to verify lead order before fitting a replacement, to look up equivalent parts, and to interpret in-circuit diode or junction readings. Open it in any standard PDF viewer and confirm the case style matches the part on your board.
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.