Part number 2SK1906 is all the name reveals about this 96.0 KB PDF, which sits in the schematic category. In the Japanese semiconductor scheme 2SK means an N-channel FET, so the file is best treated as that transistor's datasheet. It helps a technician confirm the pinout and electrical limits, judge whether a substitute with similar voltage, current and resistance will do, and identify the package. Check the maker's logo on the device, since several companies may have documented similar numbers.
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.