Farm_boy-win32-x64.7z

"farm_boy-win32-x64.7z" (If you are spelling out the letters: "ef-ay-ar-em..." )

The proper article to use before is "a." farm_boy-win32-x64.7z

Since "farm" is a common word, most people will read the filename starting with a consonant "f" sound, making the natural choice. "farm_boy-win32-x64