Younger readers, ask your parents about faxes.
Since I haven’t sent or received a fax in 15 years, I can only assume the folder was automatically installed by Windows. I’ve installed a fresh OS so it isn’t something previously hidden that Windows helpfully dragged up from the vaults.
I don’t remember seeing it before so my guess is the folder was added when I used the Windows Fax and Scan software to scan some paper documents.
Which brings me to my next question: why does Windows 8 have Fax software at all? There’s an argument for legacy stuff on a PC. This is ridiculous.