Learn Icelandic: Bara ef brælan væri búin og bylgjurnar væru minni. - If only the rough seas were over and the waves were smaller.

The phrase bara ef (if only) sets up a hypothetical wish, which triggers the subjunctive mood. To talk about an unreal situation right now, we use the past subjunctive of vera (to be). Væri is for the singular brælan, and væru is for the plural bylgjurnar.

Does brælan just mean bad weather, or is it specific to the ocean?

Bræla specifically means rough seas or bad weather at sea. Because fishing and sailing are so central to Icelandic life, there are specific words for ocean weather. If you were talking about a regular storm on land, you would usually use a word like stormur or vont veður.

Why is the word for finished spelled búin here without the double N?

The word búinn (finished or done) changes its ending to agree with the noun it describes, just like a regular adjective. Because brælan (the rough sea) is a feminine singular noun, it takes the feminine singular form búin.

Is minni (smaller) in a special plural form to match bylgjurnar (the waves)?