A 27 KB PDF named 5HN01M, filed under schematics but referring to a single discrete component. The M suffix most likely denotes a package within the 5HN01 series. The document should provide pin functions, maximum ratings and mechanical dimensions. It is useful when tracing a fault to a small switching transistor and confirming its type before replacement. Check that pin order and footprint agree with the original part, since variants of one series can be packaged differently.
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.