To "verify" something means to establish that it is TRUE. So, you can only verify things that are either true or false. You cannot verify that Bob is in a bad mood, for example, because that is subjective. However, Bob's sister, Mary, can confirm that he's in a bad mood by saying "I spoke with Bob this morning and I can declare that he is in a bad mood". That is a "confirmation". Mary is giving her affirmation. Mary might be wrong. Mary hasn't proven anything. She hasn't established the truth of anything. Mary has only given her opinion, but that opinion adds strength to the opinion that Bob is in a bad mood. That's what it means to confirm: it means lending your own authority, based on either little or a great deal of evidence, to something.