Short PDF datasheet, about 74 KB, for the PF12864-A display module, where A is likely a revision or variant letter. The 12864 part of the code usually denotes a 128 x 64 dot graphic LCD, though the document itself should confirm it. Datasheets like this list the interface pins, controller type, logic and LCD drive voltages and outline dimensions. Technicians use them when checking whether a replacement panel is a drop-in fit or when tracing a dead display back to its supply or contrast circuit.
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 @acodis_lcd_datasheets_EDID. 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.