Very small 26.9 KB PDF for the 2SK2951, likely a short datasheet or summary page given its size. The 2SK prefix marks an N-channel FET in the Japanese JIS system, so despite the schematic category it concerns a single component. It should still list pinout and key ratings useful for testing and substitution. Because the file is brief, cross-check important limits against another source and confirm the code on the original part before choosing a replacement.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)