PDF datasheet whose file name is a Texas Instruments literature number in the SDLS series, the code TI uses for its classic bipolar logic documents such as 74LS parts. The name does not say which device it covers, so open it to read the title page; at 684 KB it is probably a scanned multi-page document. Technicians use such sheets for pinouts, function tables, timing and absolute maximum ratings when diagnosing or replacing TTL logic. Confirm the part marking on the board matches the document before relying on it.
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.