"The question is difficult to answer."
Translation:Frågan är svår att svara på.
I think this is the first time I've seen svara used with på...what function does på serve here and when do you need to use it with svara?
Could you also say "Det är svårt att svara på frågan"? Or would that not work?
I'm not native, but I think that, even though they mean the same, the subject of both sentences, and thus the thing they focus on, are different.
”Svara” means ”to answer” and is commonly used together with the preposition ”på”, but not always. ”Besvara” is a seperate word which means the same thing as ”svara på”. You could say that the be- here replaces the preposition.
Another way to say this is that an intransitive or prepositional verb often has a transitive counterpart that starts with the prefix be. German and Dutch are like this, too.
In fact, English has this, too, although the verbs that do this tend to sound old or formal. Consider to belittle (to make little), to bewitch (to enchant) and to bemoan (to moan about). It's even there in adjectives formed from old past participles, like bespectacled.