Learn Hardcore Icelandic: Sólin er björt en skýjin eru þung. - The sun is bright but the clouds are heavy.

In Icelandic, verbs agree with their subject in number. Sólin (‘the sun’) is singular, so it takes er. Skýjin (‘the clouds’) is plural, so it takes eru.

Why do sólin and skýjin end with -in, and why is there a j in skýjin?

Icelandic has no separate word for “the”; the definite article is a suffix. For a feminine noun in the singular you add -in: sól → sólin (“the sun”). For a neuter noun in the plural you add -(i)n; to avoid three vowels in a row (skýiin), a j is inserted, giving skýjin (“the clouds”).

Why is the adjective björt and not björtu or björti?

After a linking verb like er, adjectives are in predicative position and use the indefinite form. They agree only in gender, number and case. Sólin is feminine singular, so its predicative adjective is the feminine singular nominative indefinite form: björt.

How do I know which form of þungur to use? Why is it þung and not þungt or þungir?

Þungur means “heavy.” In predicative position for a neuter noun in the plural, you use the neuter plural nominative form, which has no ending: þung. That matches the neuter plural subject ský.

What does en mean, and could I use og instead?

En means “but,” expressing contrast. Og means “and,” expressing addition. Using en highlights the contrast between the bright sun and the heavy clouds; og would simply link two statements without that nuance.

Can I omit the second verb and say Sólin er björt en skýjin þung?

Yes—especially in casual spoken Icelandic you can drop eru and just say skýjin þung. It’s still clear that the clouds are heavy. In formal writing, though, it’s better to include eru.

Is the normal word order always Subject–Verb–Adjective in Icelandic?

The unmarked order for simple predicative sentences is indeed Subject–Verb–Complement (adjective). You can invert for emphasis or poetic effect (e.g. Björt er sólin en þung eru skýjin), but everyday speech follows S–V–Adj.