Við komum í veg fyrir vinnuslys.

Here it is the pronoun we.

That is worth asking because við can also be a preposition in Icelandic, often meaning against, with, or by, depending on context. In this sentence, though, it is clearly the subject pronoun because it comes before the verb komum:

• Við komum ... = We ...

So grammatically this starts like a normal subject + verb sentence.

Komum is the 1st person plural form of koma.

So:

• ég kem = I come
• við komum = we come

In this sentence, the verb is part of the expression koma í veg fyrir, so you should not read it as simple physical come.

A very important detail: komum can also be the past tense 1st person plural form of koma. So by itself, við komum can mean either:

• we come
• we came

Only context tells you which one is meant.

You usually know from context, not from the verb form alone.

In Icelandic, some verb forms are ambiguous, and komum is one of them. So:

• Við komum í veg fyrir vinnuslys. could mean We prevent workplace accidents or We prevented workplace accidents, depending on the situation.

If the broader text is about a general policy, safety rules, or what a company does regularly, you understand it as present.
If the text is about something completed in the past, you understand it as past.

Learners often expect Icelandic to mark this difference clearly every time, but sometimes it does not.

Yes. Koma í veg fyrir is a fixed idiomatic expression meaning to prevent.

You should learn it as a whole unit:

• koma í veg fyrir e-ð = prevent something

Even though the individual words have more literal meanings, the full expression is what matters here. A rough literal idea is something like come in the way of / put in the way before, but that literal breakdown is not how you should translate it in normal English.

For learners, the best approach is:

• memorize koma í veg fyrir as one chunk
• then add the thing being prevented after it

Because this idiom is built that way. Icelandic often uses multi-word verb expressions where English uses a single verb.

So instead of one simple verb meaning prevent, Icelandic commonly says:

• koma í veg fyrir ...

The parts are not freely chosen here in the way an English learner might hope. In other words, you normally do not ask why not another preposition?—you simply learn that this is the established expression.

This is similar to how English learners have to memorize combinations like:

• look forward to
• run into
• put up with

They are not always predictable from the individual words.

In this expression, the noun after fyrir is normally in the accusative.

So the pattern is:

• koma í veg fyrir + accusative

In your sentence, vinnuslys does not visibly change form, so you cannot see the accusative ending. That is normal: many Icelandic nouns have the same form in nominative and accusative.

A useful thing to remember is that the whole expression governs the object:

• Við komum í veg fyrir vinnuslys.

The thing being prevented comes after fyrir.

Formally, it could be either singular or plural, because vinnuslys has the same shape in both singular and plural indefinite forms.

That happens because the base noun slys is a neuter noun whose singular and plural can look the same in some cases.

So:

• vinnuslys = a workplace accident or workplace accidents

In real use, context tells you which is intended. If the sentence is speaking generally about safety, the natural interpretation is usually workplace accidents.

This is another place where Icelandic leaves more to context than English sometimes does.

Because Icelandic strongly prefers compound nouns.

Vinnuslys is built from:

• vinnu- = work / labour (compound form)
• slys = accident

So the language combines them into one noun:

• vinnuslys = workplace accident / occupational accident

This is extremely common in Icelandic. English often writes similar ideas as two words or with an adjective + noun, but Icelandic frequently makes one compound word instead.

Because Icelandic often uses a bare noun for an indefinite or general meaning.

So:

• vinnuslys = workplace accident(s) in a general sense
• vinnuslysin = the workplace accidents

In a sentence like this, the meaning is generic: it is talking about preventing workplace accidents as a category, not a specific already-known set of accidents.

That is why no definite article appears.

As a learner, it is best to keep the expression together in its normal pattern:

• Við komum í veg fyrir vinnuslys.

Since koma í veg fyrir functions as a set expression, you should treat it almost like one verb plus its object.

Icelandic word order can vary for emphasis, style, or special sentence structure, but that is not where a learner should start. The safest default is:

• subject + koma í veg fyrir + object

So yes, advanced Icelandic can sometimes move things for discourse reasons, but for normal learning and production, keep the phrase in the standard order.

Not really.

Historically and literally, vegur means road or way, and veg is a form of that word. But in this sentence, trying to translate each part literally is less useful than learning the whole idiom.

So for practical purposes:

• do not focus too much on veg by itself here
• focus on koma í veg fyrir = prevent

That will help you understand and produce natural Icelandic much more reliably.