"The bear is an animal."
Translation:Björnen är ett djur.
Björnen är djuret. = The bear is the animal. (A somewhat strange sentence, in my opinion, in either language.)
Björnen är ett djur. = The bear is an animal. (Note that this does not have to refer to a specific bear. In English, one would probably use Bears are animals to convey the same general idea, although there's nothing wrong with The bear is an animal either.)
You could have known much earlier how to type the ö, ä and å if you had read comments in earlier lessons, because it has been asked and explained more often. There are several ways: 1. hold down the key and the accents appear. You will find the ü inder the u key, the ä under the a and the ö under the o. Or do 2, the easiest option: install a Swedish keyboard on your mobile device. BTW Duo is not stupid.