Translation:The teacher is not home.
It also means family in other context.
(BTW, why didn't Duo use "at home" ?)
In my understanding, to say someone "is not home yet" means he is out and has not yet returned. In such case we need to say 老师还没回家 in Chinese for an equivalent. That is different in meaning from "The teacher is not at home".
Also home so 回家 would mean return home or to return to your family. Home is family
It is and it's not even implicit. In Chinese 家 is not an equivalent to "House". It means Home.