Translation:It is impossible to do it that way.
I know that here the translation doesn't have an "in" but it should.
"It is impossible to do it in that way."
One could ask why is "in" necessary. It just is. We use "in" and they use "on" for this particular case. Prepositions are weird and illogical in all languages and you pretty much just have to learn them case by case.
There are countless examples of this and the more time you spend on the course the more you will notice them.
Another example would be "flowers in the meadow" versus "blommor på ängen". In this case, the Swedish makes more sense in my opinion. Sometimes the English preposition makes more sense and sometimes neither of them do!
What's confusing here is probably that in English, you can say either that way or in that way, both are correct. But in Swedish, på is necessary. That is because sätt is a different noun than way and works differently. A closer translation of it could be manner or fashion in English. I actually haven't found any very good explanation about why you can skip in in English (people just say 'for brevity' etc), but for some reason, this way has become an adverb in its own right. But that hasn't happened to ett sätt in Swedish, and ett sätt isn't something you can "do".
I think you're right, there's probably more of that in English. Also there's all that regional variation that comes from it being spoken in so many countries so far apart, which is often frustrating to us when we're trying to make the course clear and consistent.
Meanwhile I have a suggestion for this way – maybe it's because in the literal meaning, you could in principle for instance 'walk' a way in the same sense that you walk a distance. But you can't do a manner or do a fashion in English either, I think? (hope)
From my experience, it seems that English has tons of unnecessary prepositions and it is quite common for them to be omitted (especially in speech) and for the sentence to still make sense (in English, at least)?
I don't claim to be good at Swedish but I think that this happens a lot more in English.
It might be a little late, but here's the what definite or indefinite means:
"I want an apple". I'm not specifying (defining) which apple I want. As long as you bring me a fruit that qualifies as an apple, I'll be happy. That is the English indefinite form. In Swedish, that would be "ett äpple".
"I want the apple". I want a very specific apple (context should make it clear which one). Bring me any other apple and I'll bite your head off. As I have defined which one I want, this is the definite form. In Swedish, that would be "äpplet".
Unfortunately sometimes English and Swedish disagree on which form should apply in certain situation, which can be confusing and you just have to accept that, for instance, "Summer is short" (indefinite) translates to "Sommern är kort" (definite). There is no reason, it just happens to be that way.
I hope that helps!