Learn Hardcore Danish: Hendes veninde glemmer sin jakke, så hun bliver hurtigt kold. - Her female friend forgets her jacket, so she quickly becomes cold.

So sin jakke tells us the jacket belongs to veninden (the friend who forgets it).
Hendes jakke would normally point to another female person already mentioned or understood from context.

But the sentence already starts with Hendes veninde. Doesn’t hendes clash with sin?

They do different jobs here:

Hendes veninde = her female friend
- hendes here refers to some woman we’re talking about in the wider context (not mentioned in this one sentence).
- veninde (the friend) is the grammatical subject of the verb glemmer.
sin jakke = her (own) jacket, referring back to the subject of the clause, which is veninde.

So in one compact sentence:

Hendes veninde → the friend belongs to some woman we have in mind
sin jakke → the jacket belongs to the friend (the subject)

This mix of hendes and sin is very typical in Danish when you need to distinguish two different female “owners” in the same sentence.

Could sin in this sentence refer back to hendes (the woman who owns the friend), instead of the friend?

No. By default, sin/sit/sine always refers to the grammatical subject of the clause it stands in, not to another possessor mentioned inside that clause.

In Hendes veninde glemmer sin jakke:

The subject is veninde
Therefore sin must refer to veninde

If you really wanted the other woman’s jacket (the one referred to by hendes), you would say:

Hendes veninde glemmer hendes jakke.
= Her friend forgets *her jacket* (the other woman’s jacket)

Who does hun refer to in så hun bliver hurtigt kold?

Formally, hun could refer either to:

veninden (the friend who forgets the jacket), or
the other woman whose friend it is (the one referred to by hendes)

From a grammar perspective, Danish doesn’t force a unique choice here; context has to decide. In practice:

Most readers will assume hun refers to veninden, the most recent and grammatically central feminine person.
If the speaker wanted to make very clear that hun is the other woman, they’d usually rephrase, for example:
- Da hendes veninde glemmer hendes jakke, bliver hun hurtigt kold.
  (but this is still a bit ambiguous)
- Or: Da veninden glemmer hendes jakke, bliver kvinden hurtigt kold. (the woman becomes cold).

So: strictly speaking, it’s ambiguous, but most likely hun = veninden unless context suggests otherwise.

Why is it sin jakke and not something like sit jakke or sine jakke?

The form of the reflexive possessive agrees with the noun it modifies, not with the owner:

sin – for common gender singular nouns (en-words)
sit – for neuter gender singular nouns (et-words)
sine – for all plural nouns

Since jakke is an en-word (en jakke), you must use sin:

sin jakke (her/his own jacket)
sit hus (his/her own house)
sine bukser (his/her own trousers)

Why is there no article before jakke? Why not sin en jakke?

With possessive pronouns in Danish (including min, din, hans, hendes, sin etc.), you normally do not use an article:

min jakke (my jacket), not min en jakke
hendes telefon (her phone), not hendes en telefon
sin jakke (her own jacket), not sin en jakke

So sin jakke is the correct and standard form.

What exactly does glemmer mean here, and why is it in this form?

Glemmer is the present tense of the verb at glemme (to forget).

at glemme – infinitive (to forget)
glemmer – present (forget(s))
glemte – past (forgot)
har glemt – perfect (has/have forgotten)

Danish present tense with -r is used for:

Current actions
Habitual actions
Near future and “narrative present”

In your sentence, it’s a normal present: glemmer = forgets.

Why is there a comma before så in ..., så hun bliver hurtigt kold?

In Danish, it’s normal (especially with the traditional comma rules) to put a comma between two main clauses joined by a conjunction like og, men, eller, for, så.

Here we have two main clauses:

Hendes veninde glemmer sin jakke
(så) hun bliver hurtigt kold

Joined by så (so). So:

Hendes veninde glemmer sin jakke, så hun bliver hurtigt kold.

Under the newer, more relaxed comma rules, that comma can sometimes be omitted, but most people still write it here, and it’s what you will usually be taught.

What is så doing here? Is it “so” or “then”?

In this sentence, så is a coordinating conjunction meaning “so / therefore”:

Hendes veninde glemmer sin jakke, så hun bliver hurtigt kold.
= Her friend forgets her jacket, *so she quickly becomes cold.*

If så were used as an adverb meaning “then”, it would usually start the clause and cause inversion:

Så bliver hun hurtigt kold.
= Then she quickly becomes cold.

Your sentence uses så as “so / therefore”, not as “then”.

Why is it bliver kold and not just er kold?

Blive means “to become / to get” in this kind of context.

hun er kold = she is cold (a state)
hun bliver kold = she becomes / gets cold (a change into that state)

Since the coldness is a result of forgetting the jacket, Danish naturally uses bliver:

Hendes veninde glemmer sin jakke, så hun bliver hurtigt kold.
= … so she quickly *gets cold.*

What’s the function of hurtigt here, and why is it before kold?

Hurtigt is an adverb meaning “quickly”. It modifies the verb phrase bliver kold (becomes cold), telling us how fast this happens.

Word order:

hun bliver hurtigt kold
literally: she becomes quickly cold

You can also say:

hun bliver kold hurtigt

That can sound slightly more like the focus is on when / how soon she gets cold, but in many contexts both orders are acceptable. The version hun bliver hurtigt kold is very natural and common.

What’s the difference between veninde and ven?

Danish distinguishes between a male and a female friend:

ven – (usually) male friend
veninde – female friend

So:

Hendes ven glemmer sin jakke – Her male friend forgets his own jacket
Hendes veninde glemmer sin jakke – Her female friend forgets her own jacket

This gender distinction is stronger than in modern English, where friend is usually gender-neutral.