"Väinö, you are nice."
Translation:Väinö, sinä olet mukava.
Yes, mostly just as SuomihhiChang-e said, just a small correction. In the case of hän (s/he) and he (they), the pronoun could be dropped sometimes when answering to a question. Taking an example from this lesson: - Onko hän mukava? (Is s/he nice?) - On. (Yes. / Literally: (She/he/it) is.)