Hún brosir þegar vinkona hennar kemur inn með heita súpu.

Both are present tense, 3rd person singular forms.

• hún brosir = she smiles
• vinkona hennar kemur = her friend comes

The dictionary forms are:

• brosa = to smile
• koma = to come

So this sentence is describing something happening in the present, or in a vivid present-style narration.

Here þegar means when.

It introduces the time clause:

• Hún brosir = she smiles
• þegar vinkona hennar kemur inn með heita súpu = when her friend comes in with hot soup

Depending on context, þegar can sometimes feel close to when or as soon as, but when is the basic meaning here.

Because Icelandic comma use does not always match English comma use.

In a sentence like this, a following þegar clause is very often written without a comma:

• Hún brosir þegar...

So even though an English learner might expect a comma before when, the Icelandic sentence looks natural without one.

Yes. Vinkona means female friend.

That is why the sentence clearly tells you the friend is a woman or girl.

Related words:

• vinur = male friend, and often also friend in a general sense
• vinkona = female friend

So vinkona hennar is specifically her female friend.

Because Icelandic possessive patterns are often different from English.

English says:

• her friend

Icelandic very often says the equivalent of:

• friend her → vinkona hennar

So hennar comes after the noun it belongs to.

Also, hennar is the genitive form of hún, used here to show possession.

This is a very common learner question.

• hennar = her
• sinn/sín/sitt is a reflexive possessive, used when the owner is the subject of the same clause

In this sentence, the relevant clause is:

• vinkona hennar kemur inn

The subject of that clause is vinkona hennar. If you used sín, it would refer back to vinkona, not to hún from the main clause.

So:

• vinkona hennar = her friend → the friend belongs to hún
• vinkona sín would suggest her own friend, referring back to the friend herself, which is not the intended meaning here

That is why hennar is correct.

Vinkona is in the nominative because it is the subject of kemur.

In the clause:

• vinkona hennar kemur inn

the friend is the one doing the action of coming in. The subject of a finite verb is normally nominative in Icelandic.

So:

• vinkona hennar = subject
• kemur = verb

Because inn is a separate word here, like in in English comes in.

So:

• kemur = comes
• inn = in

Together:

• kemur inn = comes in

This works very much like an English verb + particle combination. In a finite verb form, Icelandic normally keeps them separate:

• hún kemur inn
• vinkona hennar kemur inn

Because heita agrees with súpu in gender, number, and case.

Here:

• súpa is feminine singular
• the phrase is in the accusative
• the adjective has strong inflection

So the correct adjective form is:

• heitur = hot
• heita súpu = hot soup, feminine singular accusative

This is one of the big things Icelandic learners have to get used to: adjectives change form to match the noun.

Here it means something like with hot soup or more naturally bringing hot soup / carrying hot soup.

So the image is:

• her friend comes in
• and she has hot soup with her

In this kind of sentence, koma inn með e-ð is best understood as come in with something or come in bringing something.

That is why the phrase feels very natural as part of the action, not just as a separate description.

Because Icelandic does not have an indefinite article like English a/an.

So Icelandic can simply say:

• vinkona = a friend / friend
• súpu = soup / a soup, depending on context

For definiteness, Icelandic often uses:

• a possessive, as in vinkona hennar = her friend
• or a suffixed definite article, for example súpan = the soup

So the lack of a separate word for a is completely normal.

Two especially important sounds here are:

• þ in þegar: like th in thing
• ú in hún and súpu: roughly like oo in food

A few helpful notes:

• Hún sounds roughly like hoon
• súpu has the same ú sound at the start
• Icelandic stress usually falls on the first syllable of the word

So even if your pronunciation is not perfect yet, getting þ and ú right will already make you sound much more natural.