'there is a black heart in the belt'

'Vyössä on musta sydän' = 'there is a black heart in the belt'. Of all the umpteen duolingo phrases I have had to endure over and over again, this one rubs me most the wrong way. I don't know why but possibly because I don't understand it. Duolingo, or at least the stage of the 'course'/torture I am at, goes on and on about fashion-related items eg there is a large diamond in that piece of jewellery (except it calls it 'jewelry'), and where is the changing room, and what kind of tie is now in fashion? I don't entirely begrudge the duolingerers all of this, because I can see how some of the phrases help to understand different kinds of sentence construction (eg the way that the large diamond phrase is constructed in Finnish is something along the lines of: in the piece of jewellery there is a large diamond, whereas of course in English our tendency would be to express it the other way around. Although it does get very far up my proverbial nose that duolingo insists that you translate 'korussa' as in the piece of jewelry, not just in the jewelry, I've been caught out with that a few times now and it sucks. 

I also can't stand the translation of 'limonadi' as 'soda pop', rather than what it obviously is, a transliteration of 'lemonade'. 

But actually all of this would be fine if it wasn't all so gruellingly repetitive but then again who am I railing against? Obviously learning a language is all about repetition and I will concede that occasionally I can find myself in a zone where I can effect a translation, a sentence construction, even very rarely a grammatical form, without thinking about it at all - it just seems natural. Now, I'm not kidding myself, I know that there's a lot more to learning a language than this, but it's a way in, isn't it, and doing it daily is valuable - as long as you are actually learning the right stuff (sometimes I am a bit alarmed when there is a discrepancy between duolingo's version of a word or phrase and google translate's - but I suppose it's possible they're both right - and that it doesn't suit their respective business models to allow for nuance.