PDF document for the 2SK2374 part, filed under schematics but named after a Japanese-registered semiconductor rather than a board. Under the JIS numbering system the 2SK prefix denotes an N-channel field-effect transistor, so the 32.9 KB file is most likely a compact datasheet. Technicians use such sheets to check pinout, package, voltage and current ratings and on-resistance before choosing a replacement MOSFET. Compare the marking on the original part with the document before substituting, and open it with any PDF reader.
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.