Questions & Answers about Fläcken på soffan är fortfarande där.
Why is it fläcken and not fläck?
Because fläcken is the definite singular form: the stain.
- en fläck = a stain
- fläcken = the stain
Swedish usually adds the definite article as an ending on the noun, instead of putting a separate word like the in front.
Why is it soffan and not soffa?
For the same reason: soffan means the sofa.
- en soffa = a sofa
- soffan = the sofa
So på soffan means on the sofa, not just on a sofa.
Why are both nouns definite in Fläcken på soffan?
Because both refer to specific things:
- fläcken = the stain
- soffan = the sofa
So Fläcken på soffan means the stain on the sofa.
This is not unusual in Swedish. Each noun is marked for definiteness on its own. It is not some special construction here; it is simply one definite noun phrase containing another definite noun phrase.