This command is called “Export” for a native XCF file. Then, it does the same thing as Export As…. At early GIMP 2.8 releases, this menu label was “Export to”. Since the version 2.8.10, “Export to” and “Export” have been renamed to “Export” and “Export As” after the manner of “Save” and “Save As”.

The name becomes “Overwriting name.extension” for an imported image. So, you can export the imported image directly in its original file format, without going through the export dialog.