Learn Hardcore Danish: Hun åbner sit vindue i stuen. - She opens her window in the living room.

sin / sit / sine – reflexive possessive (refers back to the subject of the same clause)
hans / hendes / dens / dets – non‑reflexive possessive (refers to someone/something else)

In Hun åbner sit vindue i stuen, the subject is Hun (she), and the window belongs to that same hun. So Danish uses the reflexive form:

Hun åbner sit vindue… = She opens her own window.

If you said:

Hun åbner hendes vindue i stuen, it normally means:
She opens *another woman’s window in the living room* (not her own).

So sit tells us the window belongs to hun herself.

What is the difference between sin, sit and sine?

They are all reflexive possessive pronouns meaning his/her/its/their own, and they agree with the noun they describe:

sin – with common gender (en‑words), singular
- sin bog (en bog) – his/her own book
sit – with neuter gender (et‑words), singular
- sit vindue (et vindue) – his/her own window
sine – with any plural noun
- sine bøger (bøger = plural) – his/her own books

Here, vindue is a neuter noun (et vindue), so we use sit: sit vindue.

Why is it i stuen and not something like på stuen?

The preposition i usually means in / inside and is used with rooms and enclosed spaces:

i stuen – in the living room
i køkkenet – in the kitchen
i soveværelset – in the bedroom

The preposition på (on/at) is used with many other kinds of places (e.g. på arbejde, på skolen, på bordet), but not normally with stue when you mean inside the room.

So i stuen is the natural way to say in the living room.

Why is it stuen and not just stue?

Danish usually marks definiteness on the noun with a suffix:

stue = a living room
stuen = the living room

In English, you would normally say in the living room here, not in a living room, because it refers to a specific, known living room (e.g. in her home). That is why Danish uses the definite form stuen.

What are the genders of vindue and stue, and how do they affect the sentence?

Danish has two grammatical genders:

Common gender (n‑words) – usually take en
Neuter gender (t‑words) – usually take et

For these nouns:

en stue – a living room → definite: stuen
et vindue – a window → definite: vinduet

This matters for:

The possessive pronoun:
- sin stue (common gender)
- sit vindue (neuter gender)
The definite form:
- stuen (‑en for common)
- vinduet (‑et for neuter)

So we say sit vindue because vindue is neuter (et vindue).

Could you also say Hun åbner vinduet i stuen without sit?

Yes, but the meaning changes slightly.

Hun åbner sit vindue i stuen.
Emphasizes that it is her own window.
Hun åbner vinduet i stuen.
Just says the window in the living room without explicitly stating whose it is. Context usually suggests it’s hers, but grammatically it’s just a specific, known window:
- vinduet = the window (definite form of et vindue)

So sit vindue focuses on possession; vinduet focuses on “the particular window”.

How is the verb åbner working here? It doesn’t change like English opens/open.

Danish verbs do not change with the subject in the present tense. The present is formed with ‑r (or sometimes ‑er) on the stem:

jeg åbner – I open
du åbner – you open
han/hun åbner – he/she opens
vi åbner – we open
I åbner – you (plural) open
de åbner – they open

So åbner is the same for all persons. In Hun åbner sit vindue i stuen, åbner is the present tense: opens / is opening.

Is the word order fixed? Could I say I stuen åbner hun sit vindue?

Both are grammatical, but they have different emphasis.

Neutral, most typical order:

Hun åbner sit vindue i stuen.
Subject (Hun) first, then verb (åbner), then objects and adverbial (i stuen).

If you move i stuen to the front:

I stuen åbner hun sit vindue.
This puts extra focus on the place (the living room). It can sound more narrative, like setting the scene:
In the living room, she opens her window.

So the basic word order is Subject–Verb–(Object)–(Adverbial), but you can front an adverbial like i stuen for emphasis, as long as the verb is still in the second position in the main clause (the V2 rule).

Why is it Hun and not something like Hende for “she”?

Danish distinguishes between subject and object pronouns, similar to she vs her in English:

Subject form: hun – she
Object form: hende – her

In this sentence, the pronoun is the subject of the verb åbner, so the subject form is required:

Hun åbner sit vindue i stuen. – She opens her window in the living room.

You would use hende after a preposition or as an object:

Jeg ser hende. – I see her.
Gaven er til hende. – The gift is for her.