Rennibrautin er blaut, svo pollagallinn hennar verður skítugur.

Icelandic often builds nouns as compounds, so rennibraut is a single word:

• renni- = related to renna, to slide / to glide
• braut = track, path, lane

So rennibraut means slide.

The ending -in is the suffixed definite article, so:

• rennibraut = a slide
• rennibrautin = the slide

That definite article is attached to the noun instead of being a separate word like English the.

Because adjectives in Icelandic agree with the noun they describe in gender, number, and case.

Here, rennibrautin is:

• feminine
• singular
• nominative

So the adjective must match it:

• masculine: blautur
• feminine: blaut
• neuter: blautt

Since rennibrautin is feminine, blaut is the correct form.

These two verbs do slightly different jobs:

• er = is → describes a state
• verður = becomes / gets → describes a change into a state

So:

• Rennibrautin er blaut = The slide is wet
• pollagallinn hennar verður skítugur = her rainsuit gets/becomes dirty

English often uses get where Icelandic uses verða.

Not mainly in this sentence. Although verða can sometimes help express future meaning, here it is best understood as become / get.

So verður skítugur means:

• becomes dirty
• gets dirty

not simply will be dirty.

The idea is that the wet slide causes the rainsuit to change from clean to dirty.

Here svo means so in the sense of therefore / as a result.

So the sentence structure is:

• The slide is wet, so her rainsuit gets dirty.

Be aware that svo can mean other things in other contexts, such as:

• then
• thus
• so / very

But in this sentence it is a result connector: so.

In normal Icelandic, possessors like hennar often come after the noun.

A very common pattern is:

• noun + definite article + possessor

So:

• pollagallinn hennar = her rainsuit
• literally something like the rainsuit of hers

This is the usual natural way to say it.

Because Icelandic commonly uses the definite article together with a possessive.

So English says:

• her rainsuit

but Icelandic naturally says:

• pollagallinn hennar
• literally the rainsuit her

This is normal Icelandic grammar, not emphasis or redundancy.

You see the same pattern in many everyday phrases:

• bíllinn minn = my car
• húsið þeirra = their house
• bókin hennar = her book

Pollagalli is a very Icelandic everyday word, especially for children’s clothing.

It usually means a waterproof rainsuit, often the kind a child wears outside in wet weather. It is more specific than just coat or raincoat.

The word is also a compound:

• polla- relates to puddle
• galli = suit / overalls / outfit

So the image is basically puddle-gear.

Again, adjective agreement is the reason.

The subject here is pollagallinn, which is:

• masculine
• singular
• nominative

So the adjective must match:

• masculine: skítugur
• feminine: skítug
• neuter: skítugt

That is why the sentence has skítugur.

It comes from skítur (dirt, or more literally shit), but in everyday Icelandic skítugur is the normal word for dirty.

So in this sentence it just means:

• dirty
• muddy / grimy

It is not shockingly rude here. It is a very common ordinary adjective.

Hennar is the genitive form of the third-person feminine pronoun, and it is used to show possession.

So:

• hún = she
• hana = her (object)
• henni = her (indirect object / dative)
• hennar = her / hers in a possessive sense

In this sentence, hennar means her as the owner of the rainsuit.

Because the adjective is a predicate adjective, not a direct object.

In Icelandic, after verbs like:

• vera = to be
• verða = to become

the adjective usually agrees with the subject and stays in the nominative.

So:

• pollagallinn is nominative
• skítugur matches it in nominative

The same thing happens earlier with:

• rennibrautin er blaut

Yes, but the meaning or feel can shift slightly depending on how svo is being used.

In your sentence, svo works like the conjunction so, so the clause stays:

• svo pollagallinn hennar verður skítugur

If svo is felt more like an adverb such as then, you may get verb-second word order:

• svo verður pollagallinn hennar skítugur

So both patterns can occur in Icelandic, but the original sentence is perfectly natural as written for so / therefore.

They are:

• rennibrautin → dictionary form rennibraut (slide)
• er → dictionary form vera (to be)
• blaut → dictionary form blautur (wet)
• svo → so
• pollagallinn → dictionary form pollagalli (rainsuit)
• hennar → pronoun form meaning her
• verður → dictionary form verða (to become / get)
• skítugur → dictionary form skítugur (dirty)

This is useful because Icelandic words often appear in forms that look quite different from the dictionary entry.