"Yes, this sentence is correct."
Translation:Kyllä, tämä lause on oikein.
Technically I believe that a lause is a clause (e.g. a subordinate clause, a coordinate clause, etc.), though I know informally it can be used to mean a sentence. I believe the exact equivalent to sentence is "virke". I've reported my version ("joo tämä virke on oikein") for consideration.
I welcome corrections but I believe that Finnish uses the words for "correct" differently from English. When you say that something "is correct" (i.e. a predicative use), Finnish uses an adverbial form - something like "this sentence is correctly". If you use the adjective form "oikea", it translates to something like "this sentence is the correct one". This does not apply when the adjective comes before the noun (attributive use).