PDF document for the TPS51117, a Texas Instruments single synchronous step-down controller frequently used for laptop system or memory rails; the file is catalogued as a schematic but is most likely the datasheet. At 1.39 MB it should contain pinout, typical application circuit and electrical characteristics. Technicians consult it to identify enable, power good and feedback pins, calculate output voltage from resistor dividers, and judge whether the controller is faulty. Compare the package marking on the chip with the datasheet before measuring.
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 @schematiclaptopramkushwaha. 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.