Vindurinn er svo hvass að við förum ekki út.

Vindur means wind.

The ending -inn is the definite article, so vindurinn means the wind.

Icelandic usually attaches the to the end of the noun instead of using a separate word like English does.

So:

• vindur = wind
• vindurinn = the wind

In this sentence, vindurinn is also the subject, so it is in the nominative singular.

Because hvass is a predicate adjective here: it comes after er and describes the subject.

In Icelandic, adjectives used after vera (to be) usually stay in the strong form, even if the noun is definite.

So:

• Vindurinn er hvass. = The wind is strong/sharp.

But when an adjective comes directly before a definite noun, you often get a different form:

• hvassi vindurinn = the strong wind

So hvass is correct here because it is linked to the noun through er.

Svo ... að means so ... that.

It is a very common Icelandic pattern for showing result or consequence.

So:

• svo hvass að ... = so strong that ...

In the full sentence:

• Vindurinn er svo hvass að við förum ekki út.
• The wind is so strong that we do not go out.

Sometimes, yes, but the meaning changes slightly.

• mjög hvass = very strong
• svo hvass að ... = so strong that ...

If you want the sentence to continue with a result clause introduced by að, then svo is the natural choice.

Compare:

• Vindurinn er mjög hvass. = The wind is very strong.
• Vindurinn er svo hvass að við förum ekki út. = The wind is so strong that we do not go out.

So mjög describes degree, while svo ... að sets up a consequence.

Here að means that.

It introduces the second clause:

• að við förum ekki út = that we do not go out

This is not the infinitive marker að meaning to, as in:

• að fara = to go

So Icelandic að can have more than one job, and here it is a conjunction meaning that.

Yes, fara is the infinitive, meaning to go.

Förum is the present tense form used with við (we):

• ég fer = I go
• þú ferð = you go
• hann/hún/það fer = he/she/it goes
• við förum = we go
• þið farið = you (plural) go
• þeir/þær/þau fara = they go

So við förum means we go or we are going depending on context.

This verb is a bit irregular, so the vowel changes:

• fara → fer / förum / farið

Because after the conjunction að, Icelandic normally uses ordinary subordinate-clause word order:

• að við förum ekki út

Here the subject við comes before the verb förum.

This is different from the kind of word order shifts you often see in Icelandic main clauses. In this subordinate clause, við förum is the normal pattern.

Because ekki usually comes after the finite verb and before particles or adverbs like út.

So:

• við förum ekki út = we do not go out

This is the normal order.

Breakdown:

• við = we
• förum = go
• ekki = not
• út = out / outside

Putting ekki after út would sound wrong in standard Icelandic.

Út is an adverb/particle meaning out or outside.

With the verb fara, it often means to go out:

• fara út = go out

So við förum ekki út means we are not going outside / we do not go out.

It works much like a particle in English expressions such as go out, come in, walk away, and so on.

Here it means we.

Icelandic við can be:

• a pronoun = we
• a preposition = with

In this sentence, it must be the pronoun, because it is the subject of förum:

• við förum = we go

If it meant with, the sentence structure would be completely different.

Vindurinn is in the nominative case because it is the subject of the sentence.

The sentence is saying something about the wind:

• Vindurinn er svo hvass ...
• The wind is so strong ...

Subjects are normally nominative in Icelandic, so vindurinn is nominative singular.

Not only sharp.

Hvass can mean things like:

• sharp
• keen
• severe
• strong (especially about wind)

So when talking about weather, hvass vindur or vindurinn er hvass means the wind is strong, harsh, or cutting.

That is a very natural Icelandic way to describe strong wind.