Atvinnurekandinn skrifar í slysaskrána.

The ending -inn is the suffixed definite article, so atvinnurekandinn means the employer.

The base noun is atvinnurekandi = employer.
Adding -inn makes it definite:

• atvinnurekandi = an employer / employer
• atvinnurekandinn = the employer

This is very common in Icelandic: instead of a separate word like English the, Icelandic usually attaches the definite article to the end of the noun.

skrifar is the present tense, 3rd person singular form of the verb skrifa = to write.

So:

• ég skrifa = I write / am writing
• þú skrifar is not correct
• hann / hún / það skrifar = he / she / it writes / is writing

In this sentence, atvinnurekandinn skrifar means the employer writes or the employer is writing. As in many languages, the simple present can cover both a general action and an action happening now, depending on context.

Because Icelandic usually expresses the by attaching it to the noun.

In this sentence:

• atvinnurekandinn = the employer
• slysaskrána = the accident register / the accident log

So the sentence already contains the twice, just not as a separate word.

This is one of the first big differences English speakers notice in Icelandic grammar.

The preposition í can take two different cases in Icelandic:

• accusative when there is movement or direction into
• dative when something is in a place

Here we get slysaskrána, which is accusative singular definite. The idea is that the writing is being entered into the accident record.

So the phrase is understood as something like:

• write into the accident register

This is a useful general pattern:

• í skólann = into the school
• í skólanum = in the school

With verbs like skrifa, the choice can reflect how the action is viewed. In this sentence, the accusative fits the idea of making an entry into the record.

It is a compound noun plus the definite ending.

You can break it down like this:

• slys = accident
• skrá = register, record, log
• slysaskrá = accident register / accident log
• slysaskrána = the accident register in the accusative singular

So Icelandic often builds longer nouns by combining smaller words. English does this too, but Icelandic does it very productively.

Because the main noun in the compound is skrá, and skrá is a feminine noun.

In Icelandic compounds, the last element usually determines the grammatical gender. Since skrá is feminine, slysaskrá is also feminine.

That matters for its endings. For example:

• slysaskrá = indefinite nominative singular
• slysaskrána = definite accusative singular

So even though slys comes first, the gender is determined by skrá.

It does not have to be stated. Icelandic, like English, can leave out the direct object when it is obvious from context or not important.

So Atvinnurekandinn skrifar í slysaskrána means something like:

• The employer writes in the accident log
• The employer makes an entry in the accident register

The sentence focuses on where the writing goes, not on what is being written. If needed, Icelandic could include the thing being written, but it does not have to.

The sentence has a very normal default word order:

• Atvinnurekandinn = subject
• skrifar = verb
• í slysaskrána = prepositional phrase

So it follows the common pattern subject + verb + other information.

However, Icelandic word order is somewhat flexible because of the verb-second pattern. You can move another element to the front for emphasis, but then the finite verb still normally stays in second position.

For example:

• Í slysaskrána skrifar atvinnurekandinn.

That can sound more marked or emphatic. The original sentence is the most neutral and straightforward version for a learner.

You would remove the suffixed definite article from the nouns.

That gives:

• Atvinnurekandi skrifar í slysaskrá.

This would mean something like An employer writes in an accident register or An employer writes in an accident log, depending on context.

Compare:

• atvinnurekandi = an employer
• atvinnurekandinn = the employer
• slysaskrá = an accident register
• slysaskrána = the accident register (accusative)

So the endings are doing important grammatical work in the original sentence.