Learn Swedish: Kören sjunger i kyrkan på söndagar. - The choir sings in the church on Sundays.

Because the choir sings every Sunday. To talk about a habit or repeated event on a specific day of the week, Swedish uses på followed by the plural form of the day (söndagar). If you said på söndag (singular), it would mean just this upcoming Sunday.

Why does the sentence use the definite form kyrkan (the church) when English often just says 'in church'?

Swedish frequently uses the definite form for public institutions or familiar places (like kyrkan, skolan, or banken) when talking about their typical function, even when English drops the word 'the'.

If I want to start the sentence with 'On Sundays...', how does the word order change?

It becomes På söndagar sjunger kören i kyrkan. Because Swedish is a 'verb-second' (V2) language, the verb (sjunger) must be the second block of information. Moving the time phrase to the front pushes the subject (kören) directly after the verb.

Do kören and kyrkan start with a hard 'k' sound like in English?

No, both of these words start with a soft 'k' sound because they are followed by the 'soft' vowels ö and y. It sounds similar to an English 'sh' or 'ch' sound, depending on the dialect.