Det er fire timer siden, hun sidst gik rundt i lejligheden, så nu hviler hun sig igen.

In this sentence, det does not refer to a specific thing. It is a dummy subject, like English it in It is four hours since...

So:

• Det er fire timer siden ... = It has been four hours since ...

Danish often uses det er in time expressions like this.

Examples:

• Det er længe siden. = It has been a long time.
• Det er tre dage siden, vi så ham. = It’s been three days since we saw him.

Here, siden means something like since in the structure Det er X tid siden ...

So:

• Det er fire timer siden, hun sidst gik rundt i lejligheden
  = It has been four hours since she last walked around the apartment

English speakers sometimes think of this as similar to ago, but grammatically it is closer to since in this pattern.

Compare:

• for fire timer siden = four hours ago
• det er fire timer siden ... = it has been four hours since ...

These are related, but they are not built the same way.

Because the action happened four hours earlier, Danish normally uses the simple past here:

• hun sidst gik rundt i lejligheden = she last walked around the apartment

This is very natural in Danish after Det er ... siden.

Examples:

• Det er to år siden, jeg flyttede. = It’s been two years since I moved.
• Det er længe siden, vi talte sammen. = It’s been a long time since we spoke.

English sometimes uses present perfect in nearby situations, but in this Danish pattern, the past tense is very common and normal.

Sidst means last or most recently.

So:

• hun sidst gik rundt i lejligheden = she last walked around the apartment

It tells you that this was the most recent time she did that action.

Its position is normal in Danish subordinate clauses. Since this clause comes after siden, the word order is subordinate-clause word order, so adverbs like sidst often come before the finite verb:

• hun sidst gik ...

Compare:

• Hun gik sidst rundt i lejligheden is not the natural wording here for the same meaning.

Gå rundt means walk around, move around, or go about within an area.

So:

• gå i lejligheden could sound incomplete or mean simply walk in the apartment
• gå rundt i lejligheden clearly means walk around the apartment

The word rundt adds the idea of movement within the space, not just one step or one direction.

Examples:

• Han gik rundt i haven. = He walked around the garden.
• Barnet løb rundt i huset. = The child ran around the house.

The commas mark clause boundaries.

1. Det er fire timer siden, hun sidst gik rundt i lejligheden

   • The part after siden is a subordinate clause.
   • Danish often places a comma before subordinate clauses.

2. ..., så nu hviler hun sig igen

   • så here means so, introducing a new main clause.
   • A comma before så is normal when it connects clauses like this.

So the commas help show the structure:

• main clause: Det er fire timer siden
• subordinate clause: hun sidst gik rundt i lejligheden
• new main clause: så nu hviler hun sig igen

This is because Danish main clauses follow the V2 rule: the finite verb usually comes in the second position.

Here, nu is placed first in the clause for emphasis or flow:

• så nu hviler hun sig igen

Structure:

• så = coordinating conjunction
• nu = first element of the new clause
• hviler = finite verb in second position
• hun sig igen = rest of the clause

So the clause is built like this:

• Nu hviler hun sig igen.

That is why you do not say:

• så nu hun hviler sig igen ❌

And så hun hviler sig nu igen would change the structure and sound unnatural in this context.

Hvile sig is a common reflexive expression meaning to rest or to have a rest.

So:

• hun hviler sig = she is resting

The sig is the reflexive pronoun, like herself, though in English we usually do not say she rests herself in this context.

Reflexive pronouns in Danish:

• jeg vasker mig = I wash myself
• han sætter sig = he sits down
• hun hviler sig = she rests

In modern Danish, hvile can also appear without sig in some contexts, but hvile sig is very common when talking about a person taking rest.

Igen means again.

So:

• nu hviler hun sig igen = now she is resting again

Putting igen near the end is very natural in Danish. It modifies the whole action: she is doing this once more.

Danish word order often places short adverbs like this later in the clause unless there is a special reason to emphasize them elsewhere.

Compare:

• Hun prøver igen. = She tries again.
• Han er hjemme igen. = He is home again.

Yes. Lejligheden is the definite singular form of lejlighed.

• en lejlighed = an apartment / a flat
• lejligheden = the apartment / the flat

Danish usually adds the definite article to the end of the noun:

• bog = book

• bogen = the book

• lejlighed = apartment
• lejligheden = the apartment

So i lejligheden means in the apartment.

Yes, lejlighed can mean either:

• apartment / flat
• opportunity / occasion in some contexts

But the context makes the meaning clear here.

• gik rundt i lejligheden can only naturally mean walked around the apartment

You cannot really walk around in an opportunity, so the physical-space meaning is the only sensible one here.

Yes, in this sentence så means so in the sense of therefore / as a result.

• ..., så nu hviler hun sig igen. = ..., so now she is resting again.

But Danish så has several uses, so it does not always translate as so:

• så = so / therefore
• så = then
• så = so / very in some contexts

Here it is clearly the logical connector: one thing leads to another.

Not exactly. The Danish sentence does not say that she has continuously avoided walking around for four hours. It says that the last time she walked around the apartment was four hours ago.

So the best match is something like:

• It has been four hours since she last walked around the apartment, so now she is resting again.

That is different from:

• She hasn’t walked around the apartment for four hours

The second version focuses more directly on the whole four-hour period of non-action. The Danish sentence focuses on the time elapsed since the last occurrence.