Translation:That is true.
In a real situation, I could definitely see someone translating this as, "Truth!" However, we do not accept it in this course because we do not want there to be confusion about whether it is a noun or a verb. The word teH is only a verb meaning "to be true". There is a separate noun vIt which means "truth".
So the bare verb teH. as a full sentence would officially be translated as, "It is true." Notice the "is" comes from conjugating the "to be" in the original definition.
Klingon does not have the demonstrative pronouns "this", "that", "those", and "these". You will learn later how to translate those as relative pronouns (connected to a noun). But to say "That is true," it is probably best to just say, "It is true," which would be teH.