Learn Finnish: Tämä murre on vaikea, joten voitko sanoa sen ruotsiksi? - This dialect is difficult, so can you say it in Swedish?

In Finnish, the Translative case (-ksi) is used to express the language of communication. Whenever you talk about speaking, writing, or saying something "in" a language, you attach -ksi to the language name. Using ruotsissa would literally mean physically being inside the country of Sweden!

Why is the object "it" translated as sen here, rather than the partitive sitä?

The verb sanoa (to say) takes a total object when you are referring to a complete thought, word, or phrase being said. Because you are asking someone to say a specific complete thing, it takes the genitive-accusative form sen. You would use sitä if the action was ongoing or incomplete.

How does joten differ from other connecting words like koska or että?

Joten means "so" or "therefore," and it introduces the logical result of the first phrase (The dialect is hard, so say it in Swedish). It is the opposite of koska (because), which introduces the reason. Että simply means "that" and wouldn't fit the logic here.

Does tämä murre need to change its form if I instead say "I speak this dialect"?

Yes! When used as the object of a verb like puhua (to speak), which always takes a partitive object, both the pronoun and the noun must change to match. You would say Puhun tätä murretta.