Part number 2SB1209 with an _E suffix identifies this 42.6 KB PDF, filed under schematics though a single-part document of this kind is normally a datasheet. JIS assigns the 2SB prefix to PNP low-frequency transistors. The sheet helps identify base, collector and emitter for in-circuit diode tests, and lists maximum ratings and hFE classes for picking a replacement. Before relying on it, make sure the marking and package on the failed component agree with what the document shows.
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.