PDF document of 885 KB whose Persian file name translates as oscilloscope, which suggests a guide or tutorial on using an oscilloscope rather than a schematic for a specific device. No brand, model or board is named, so open it to see whether it covers basic operation, probing technique or reading waveforms. An oscilloscope is the tool for checking clock signals, PWM switching on buck converters, ripple on power rails and data activity, things a multimeter cannot show. Content language is likely Persian.
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 @datasheets1. 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.