Видеть (it's the infinitive for "видит") - means "to see". It's the result of looking at something. I look at you and see you.

Увидеть (it's the infinitive for "увидит") - means the result of seeing someone/something. There is no exact equivalent for "увидеть" in English, it's usually expressed by Future Indefinite tense: I will see something/someone.