This 200 KB PDF is labelled 100BGQ015J, a part code that follows Schottky rectifier naming, and although indexed as a schematic it is probably the datasheet for that diode variant, with the J suffix marking a package or lead option. It should give forward drop, reverse voltage and current ratings plus mechanical drawings. Repair work uses it to verify a substitute in rectifier or OR-ing circuits. Check the suffix against the original component, since package variants are not always interchangeable.
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.