I'm being charged $39.00 a month on my iPhone for iCloud, why?

There isn't anything that I can think of related to iCloud that costs anywhere near $39 a month so I'm not sure what that might be but you can use the following information to see what it is for.

See the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see apple.com/bill, itunes.com/bill, or an unfamiliar charge on your statement - Apple Support

If the only indication of the charges is from an email or text, be aware that it may be a phishing attempt to get you to log in to a site that appears to be Apple and divulge your password or credit card information. See: Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

and Identify legitimate emails from the App Store or iTunes Store - Apple Support