will logging out of icloud delete everything?

I currently use my iPad for school and will need to often back up, I prefer icloud because it is much easier for me to use. From about 30-something weeks ago my icloud email logged out because it had become unusable for some reason , most likely because I accidentally put the password in wrong too many times and the email is blocked. I want to use icloud again but I am too scared to log out because it says it will delete everything on the device that is stored in icloud although I do not exactly know what is stored in it I don't want anything valuable to be deleted. Is there a way to choose what can be deleted or will everything be deleted no matter what?