When I click on restore backups and it gives me a choice between daily and weekly, and i click on one...what happens next?

I've never done it before and I don't want to do anything unless I'm sure I know what it's going to do? Can someone explain to me the process of the restoration?

I'm a bit terrified of doing stuff in WHM, becuase it tends not to give any confirmation of actions you want to perform. For instance, terminating an account will do so without even a confirmation.