Affirmation
Affirming, Positive
noun, verbal noun
An agreement is determined by means of affirmation. If both parties are affirming each other's positions, then it's safe to say they probably agree on things.
肯定 is a relatively formal word used for affirming something as correct or valid. It can describe actively agreeing with an opinion or stance, but it's more often used to describe a clear, positive response to a question or claim. It also commonly appears in introspective contexts, like 自己肯定感 (a feeling of self-acceptance), when talking about recognizing yourself or your own life in a positive way.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
どうして肯定も否定もしないんですか。
Why won't you confirm or deny it?
まずは自分を肯定してみてください。
First of all, try to affirm yourself.
その肯定の気持ち、これからも大切にしてね。
Hold on to that sense of affirmation.