"i have quickbooks mac 2016 and my accountant who has windows pc asked me to send a backup of my quickbooks file and that the file has the extension .QBB or .QBW. How do I do that?"
Hello there, sbd1.
Welcome aboard to the QuickBooks Community. It would be my pleasure to help you create a backup copy of your company file in QuickBooks Desktop for Mac.
You can create a copy of your company file in QBB format for Windows from the Mac version.
For additional insights regarding creating the backup copy, I'm adding the article I recommend on this (scroll down to Convert your Mac company file to a Windows file):
For any additional questions or concerns you may have, feel free to reach out to me. The Community is always here for you.