Hún keypti hettupeysu og gallabuxur í verslunarmiðstöðinni, en stuttermabolurinn var of dýr.

Because keypti takes a direct object, and the direct object here is in the accusative case.

The base form is hettupeysa = hoodie.
But after keypti = bought, it changes to the accusative singular:

• nominative: hettupeysa
• accusative: hettupeysu

So Hún keypti hettupeysu means She bought a hoodie.

Because gallabuxur means jeans, and like English pants/trousers, it is normally used in the plural.

So even if you are talking about one pair of jeans, Icelandic usually uses the plural form:

• gallabuxur = jeans

That is very normal and not something special to this sentence.

There are two things happening here:

1. í can take different cases in Icelandic.
2. verslunarmiðstöðinni includes the definite article, so it means in the shopping mall / shopping center.

After í, Icelandic uses:

• accusative for motion into something
• dative for location in something

Here the meaning is location: she bought the clothes in the shopping center, not into the shopping center. So í takes the dative.

The noun is:

• nominative: verslunarmiðstöð
• dative definite: verslunarmiðstöðinni

So:

• í verslunarmiðstöðinni = in the shopping center

That ending shows both:

• the dative singular
• the definite article = the

The basic noun is verslunarmiðstöð.
When it becomes the shopping center in the dative singular, it becomes verslunarmiðstöðinni.

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

Because stuttermabolurinn means the T-shirt, while stuttermabolur means a T-shirt or just T-shirt as a dictionary form.

Here the speaker is referring to a specific T-shirt, so Icelandic uses the definite form:

• stuttermabolur = T-shirt
• stuttermabolurinn = the T-shirt

Again, Icelandic usually adds the definite article to the end of the noun.

Because dýr is a predicate adjective after the verb vera = to be. Predicate adjectives agree with the noun they describe.

Here the subject is stuttermabolurinn, which is:

• masculine
• singular
• nominative

The matching adjective form is dýr.

So:

• stuttermabolurinn var of dýr = the T-shirt was too expensive

Of means too in the sense of excessively.

So:

• of dýr = too expensive
• of stór = too big
• of lítill = too small

It comes before the adjective, just like English too.

En means but.

It connects two clauses:

• Hún keypti hettupeysu og gallabuxur í verslunarmiðstöðinni
• en stuttermabolurinn var of dýr

So the sentence means that she bought some things, but the T-shirt was too expensive.

Because Icelandic usually uses a suffixed definite article. That means the is attached to the noun.

Examples from this sentence:

• verslunarmiðstöðinni = the shopping center (in dative form)
• stuttermabolurinn = the T-shirt

This is one of the biggest differences from English. Instead of putting the before the noun, Icelandic often adds an ending.

Yes. The verb is kaupa = to buy, and keypti is the past tense form meaning bought.

So:

• ég kaupi = I buy
• hún kaupir = she buys
• hún keypti = she bought

The vowel change from kaupa to keypti is just part of how this verb is formed in the past tense.

Because this sentence uses a very basic main-clause pattern:

• Hún = subject
• keypti = verb
• hettupeysu og gallabuxur = object

And in the second clause:

• stuttermabolurinn = subject
• var = verb
• of dýr = complement

So the order looks familiar to an English speaker. However, Icelandic word order can change more than English because the case system shows what each noun is doing.

Yes. Icelandic makes a lot of compound nouns, just like English does, but often writes them as one word.

Examples here:

• hettupeysa = roughly hood + sweater/shirt → hoodie
• verslunarmiðstöð = shopping/trade + center → shopping center
• stuttermabolur = short-sleeve + shirt → T-shirt
• gallabuxur = denim + trousers → jeans

This is very normal in Icelandic, so long words are often easier to understand once you spot the parts.

In normal Icelandic, the subject pronoun is usually stated, so hún = she is expected here.

Unlike some languages, Icelandic does not usually drop subject pronouns in ordinary sentences. So:

• Hún keypti... = She bought...

sounds natural and complete.

Yes, they matter a lot in Icelandic because gender affects endings.

The nouns here have different genders:

• hettupeysa = feminine
• verslunarmiðstöð = feminine
• stuttermabolur = masculine
• gallabuxur = plural noun, usually treated as feminine plural

Gender helps determine:

• noun endings
• adjective endings
• definite article endings
• sometimes pronoun choice

So learning the gender of a noun is an important part of learning the noun itself.