Skyndihjálpin hjálpar starfsmanninum.

Because Icelandic usually adds the definite article directly to the end of the noun instead of using a separate word like English the.

• skyndihjálp = first aid
• skyndihjálpin = the first aid

Here, -in is the feminine singular definite ending in the nominative form.

In Icelandic, the is very often a suffix, not a separate word.

So instead of:

• English: the employee
• Icelandic: starfsmanninum

and instead of:

• English: the first aid
• Icelandic: skyndihjálpin

A separate definite article does exist in Icelandic in some contexts, but in ordinary sentences like this, the suffixed article is the normal pattern.

Because hjálpa takes the dative case for the person being helped.

The dictionary form is:

• starfsmaður = employee / worker

But after hjálpa, it changes to the dative:

• starfsmanni = to an employee
• starfsmanninum = to the employee

So the ending -num shows both:

• dative singular
• definite meaning the employee

Because that is the case pattern required by the verb hjálpa.

In Icelandic, different verbs govern different cases. English learners often expect the direct object to be accusative, but Icelandic does not always work that way. With hjálpa, the person receiving help is in the dative.

So:

• hjálpa einhverjum = to help someone
• Skyndihjálpin hjálpar starfsmanninum. = The first aid helps the employee.

This is something you usually just have to learn with the verb.

Because hjálpar is the present tense form for he/she/it.

The infinitive is:

• að hjálpa = to help

Present tense:

• ég hjálpa = I help
• þú hjálpar = you help
• hann/hún/það hjálpar = he/she/it helps

Since skyndihjálpin is a singular subject, the verb has to be singular too:

• Skyndihjálpin hjálpar ... = The first aid helps ...

The main dictionary forms are:

• skyndihjálp = first aid
• að hjálpa = to help
• starfsmaður = employee / worker

The sentence uses inflected forms:

• skyndihjálpin = definite nominative singular
• hjálpar = present tense
• starfsmanninum = definite dative singular

There are two big clues:

1. Case

   • skyndihjálpin is in the nominative form, which is the usual subject case.
   • starfsmanninum is in the dative, which fits the object required by hjálpa.

2. Verb meaning and pattern

   • hjálpa normally has someone in the dative receiving help.

So Icelandic grammar, not just word order, tells you who is doing the helping.

Yes, Icelandic word order is more flexible than English, but the meaning is still controlled largely by case endings.

This sentence has the straightforward order:

• Skyndihjálpin hjálpar starfsmanninum.

But Icelandic often follows a verb-second pattern in main clauses, so if another element comes first, the verb usually comes second:

• Núna hjálpar skyndihjálpin starfsmanninum.
  Now the first aid helps the employee.

Because the noun endings show the roles, Icelandic can move parts around more freely than English.

Yes. Skyndihjálp is a feminine noun.

That matters because the definite ending and some other forms depend on gender. In this sentence, the feminine nominative singular definite form is:

• skyndihjálpin

Gender is an important part of Icelandic noun learning, so it is a good idea to memorize nouns together with their gender.

Because definiteness does not always match perfectly between English and Icelandic.

In Icelandic, adding the article can make the noun feel more specific or context-based. Without the article:

• Skyndihjálp hjálpar starfsmanninum.

that sounds more like first aid helps the employee in a general sense.

With the article:

• Skyndihjálpin hjálpar starfsmanninum.

it sounds more like the first aid or the first-aid treatment/help in a specific situation.

So the article choice can depend on context, and it will not always translate word-for-word into natural English.

In modern Icelandic, hj is usually pronounced like a hy sound, not like the English j in job.

So hjálpa begins roughly like:

• hyalp-

Also, Icelandic pronunciation is often different from spelling in ways English speakers do not expect, so it helps to learn words by listening as well as reading.