PDF datasheet filed under the Texas Instruments literature number SDLS117, a code TI assigns to its older 54/74-series TTL logic documents. The file name states only the document code, not the device it covers, so open the 287 KB file to see which part it describes. A datasheet like this gives you the pinout, truth table, supply limits and switching characteristics. Those let you check logic levels with a probe and confirm that a replacement chip is compatible before you desolder the original from the board.
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 @datasheet_technar_org. 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.