Et egern sad et øjeblik på hegnet og løb derefter ud på en gren over græsset.

Because egern is a neuter noun in Danish, so it takes et in the indefinite singular.

• et egern = a squirrel
• egernet = the squirrel

In Danish, every noun has a grammatical gender, usually either common gender (en) or neuter (et). Unfortunately, this often has to be learned word by word.

In the same sentence, you can see both genders:

• et egern
• et øjeblik
• en gren

So egern and øjeblik are neuter, while gren is common gender.

Yes. Et øjeblik literally means a moment.

In this sentence, sad et øjeblik means sat for a moment or sat there briefly.

Danish often uses a noun phrase like this without adding a separate word for for:

• Han ventede et øjeblik. = He waited a moment.
• Hun stoppede et sekund. = She stopped for a second.

So this is a very natural time expression in Danish.

Because sidde is an irregular verb.

Its main forms are:

• sidde = to sit
• sidder = sit / is sitting
• sad = sat / was sitting
• siddet = sat

So:

• Et egern sad ... = A squirrel sat / was sitting ...

This is just something you need to memorize, much like irregular verbs in English:

• sit → sat
• drink → drank
• run → ran

Danish has quite a few strong or irregular verbs like this.

Because sad describes the squirrel’s state or position, while satte sig would describe the action of sitting down.

Compare:

• Egernet sad på hegnet. = The squirrel was sitting on the fence.
• Egernet satte sig på hegnet. = The squirrel sat down on the fence.

In your sentence, the idea is that the squirrel was sitting there for a moment, and then it ran off. So sad is the natural choice.

Hegnet is the definite singular form of hegn, which means fence (or sometimes a kind of enclosed boundary/hedge, depending on context).

• et hegn = a fence
• hegnet = the fence

Danish usually makes nouns definite by adding the definite ending to the noun itself, instead of using a separate word like the.

Examples:

• en gren = a branch

• grenen = the branch

• et hegn = a fence
• hegnet = the fence

So på hegnet means on the fence.

Because the first noun is definite and the second is indefinite.

• på hegnet = on the fence / on the specific fence
• på en gren = onto a branch / onto one branch

The speaker treats the fence as something already identifiable in the scene, but the branch is introduced as a branch.

This is very similar to English:

• on the fence
• onto a branch

In Danish, when two verbs share the same subject and are joined by og (and), the subject is often omitted in the second part.

So:

• Et egern sad ... og løb derefter ...

means:

• A squirrel sat ... and then ran ...

The subject et egern still applies to both verbs:

• sad
• løb

You could repeat the subject, but it would usually sound less natural unless you wanted extra emphasis:

• Et egern sad et øjeblik på hegnet, og det løb derefter ...

That is grammatical, but the version without repeating the subject is smoother and more common here.

Derefter means after that, afterwards, or simply then.

In your sentence:

• og løb derefter ud på en gren ...
• and then ran out onto a branch ...

Its position is natural because it modifies the verb løb.

Danish adverbs like derefter, så, senere, and aldrig can move around somewhat depending on structure and emphasis, but løb derefter is completely normal.

For example:

• Han spiste og gik derefter hjem. = He ate and then went home.

Ud på expresses movement outward and onto something.

Here:

• løb ud på en gren = ran out onto a branch

It helps to break it up:

• ud = out
• på = on / onto

Together, they describe direction very naturally:

• gå ud på altanen = go out onto the balcony
• løbe ud på vejen = run out onto the road

So in your sentence, the squirrel moves from the fence to a branch extending outward.

Because the squirrel ends up on the branch, not just toward it.

Danish often uses på for movement onto a surface or position:

• hoppe op på bordet = jump up onto the table
• sætte sig på stolen = sit down on the chair
• løbe ud på en gren = run out onto a branch

By contrast, til usually means to / toward a destination in a more general sense:

• gå til skolen = go to the school
• løbe hen til døren = run over to the door

So på en gren is the right choice because a branch is something you can be physically on.

Here it most naturally means above the grass, not across the grass.

So:

• en gren over græsset = a branch above the grass

The branch extends over the grassy area below.

Danish over can sometimes correspond to English over, above, or across, depending on context. In this sentence, because it describes where the branch is located, above is the best interpretation.

Compare:

• Fuglen fløj over huset. = The bird flew over the house.
• Grenen hang over græsset. = The branch hung over the grass.

Because græsset is the definite form: the grass.

• græs = grass
• græsset = the grass

In Danish, mass nouns can also take the definite ending when you mean a specific grass area in the scene.

So:

• over græsset = over the grass

This sounds natural if the speaker has a particular patch or area of grass in mind.

The Danish ø is a front rounded vowel that English does not really have.

A useful approximation is:

• start with the vowel sound of bed or bird (depending on accent),
• but pronounce it with rounded lips.

So ø is not the same as:

• o
• u
• e

In øjeblik, the first syllable is roughly something like UR-ye or EUH-ye, but no English spelling gives it perfectly.

The word is approximately:

• øjeblik → something like UH-ye-blik / UR-ye-blik

The best approach is to hear native audio and imitate it, because Danish vowels are one of the hardest parts for English speakers.

Yes, it is completely normal.

The structure is:

• Et egern — subject
• sad — verb
• et øjeblik — time expression
• på hegnet — place
• og løb derefter ud på en gren over græsset — second coordinated verb phrase

Danish main clauses usually follow verb-second order, meaning the finite verb comes early in the clause. Here the subject comes first, so the verb follows it directly:

• Et egern sad ...

Then the second action is coordinated with og:

• og løb derefter ...

So for a learner, this sentence is a good example of straightforward, natural narrative word order.