Learn Icelandic: Hún talar norsku og sænsku. - She speaks Norwegian and Swedish.

In Icelandic, names of languages, nationalities, and adjectives derived from countries are not capitalized, unlike in English. You only capitalize them if they are the very first word of a sentence.

Why do both languages end in '-u' instead of '-a'?

The names of these languages in their base (nominative) form are norska and sænska. They are weak feminine nouns. Because they are the direct objects of the verb talar (speaks), they take the accusative case, which changes the ending from -a to -u.

Does the verb tala always take the accusative case for languages?

Yes! When you talk about speaking a language, the verb tala takes a direct object in the accusative case. This is why we say tala íslensku or, as in this sentence, tala norsku.

Could I use the verb kunna instead of talar in this sentence?

Yes, but the meaning shifts slightly. Hún kann norsku og sænsku means 'She knows Norwegian and Swedish' (focusing on her language skills). Hún talar... simply focuses on the fact that she speaks them. Both are very common and natural.