Translation:Do the walls have the ability to listen?
If I were translating a novel or story, and wanted the English version to sound authentic, I'd certainly choose the more idiomatic: "Do walls have ears?". But I assume that's not what's expected here, especially as "vermogen" ("ability") is one of the abstract nouns we're supposed to be learning. Then again, occasionally Duolingo does throw in an idiom or two, and the literal translation is rejected!
The problem is that the course is inconsistent. There are a couple of examples in other lessons where idiomatic, rather than literal, translations were also accepted. The course has to choose one—either idioms are accepted, or they aren't.
You're right that "ability" is a noun we're supposed to learn here, so if idiomatic translations are accepted, this sentence should be changed to another one where you HAVE to translate "ability".
I think accepting idioms and literal translations are both fine. One gives you an understanding of the sentence structure, the other a better sense of real language use. Idioms are one of the things that really confuse people who have started feeling confident enough to try to speak a language. They understand a lot, and then an idiom is thrown at them - like this course. So far, I like the sentences used here much better than those in either Spanish or Portuguese, they seem more like things you might hear in casual conversation.
Edit : I tried Do the walls have ears in a second attempt at this question - not accepted. The strength bar is nice - it lets you try things you otherwise wouldn't.
I'm not sure what to call the bar thingy that replaced hearts on the PC. And my favorite in the Dutch course so far is Ï can't take my backpack on the plane because there is a rhinoceros in it." But - substitute something else (like a half completed knife that my brother was making one time) - and the sentence works beautifully.