Zip archive of 1.49 MB for the Gigabyte GA-EG31M-S2 micro-ATX motherboard, with no revision or content type stated in the name. It likely contains service schematics or BIOS files; extract it to confirm. Such files help diagnose no-power, no-POST and short-circuit faults by showing rail structure, controller pinouts and component locations. Gigabyte uses separate revisions with different layouts and firmware, so compare the revision printed on your PCB before using values or flashing an image.
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 @schematicslaptop. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.