Når babyen kaster en legeklods, kigger hunden på hende.

In Danish, the definite article is usually attached to the end of the noun.

• baby = a baby
• babyen = the baby

So babyen means the baby. This is different from English, where the is a separate word.

The same pattern works with many common-gender nouns:

• en hund = a dog
• hunden = the dog

Because one noun is indefinite and the other is definite.

• en legeklods = a toy block
• babyen = the baby

Danish usually shows this contrast like this:

• en/et + noun for a/an
• noun + -en/-et for the

So here:

• en legeklods = an indefinite object, a toy block
• babyen = a specific baby already understood in the context, the baby

Når means when here.

It is used to introduce a time clause:

• Når babyen kaster en legeklods = When the baby throws a toy block

A useful beginner rule is:

• når is often used for things that happen repeatedly, generally, or in the present/future
• da is often used for a single event in the past

So this sentence sounds like a general situation or a present-time description, not one specific past event.

This is because Danish is a verb-second language in main clauses.

The sentence starts with a subordinate clause:

• Når babyen kaster en legeklods

After that, the main clause begins. In a Danish main clause, the finite verb normally comes in the second position, so you get:

• kigger hunden på hende

not

• hunden kigger på hende

So the structure is:

1. subordinate clause first
2. then the finite verb of the main clause
3. then the subject

If you put the main clause first, you would get normal subject-verb order:

• Hunden kigger på hende, når babyen kaster en legeklods.

The comma separates the subordinate clause from the main clause.

• Når babyen kaster en legeklods, = subordinate clause
• kigger hunden på hende. = main clause

Danish writing often marks this boundary clearly with a comma. So the comma helps show the sentence structure.

Because the verb kigge normally goes with the preposition på when it means look at.

So:

• kigge på nogen = look at someone
• kigge på noget = look at something

That means hende is not a direct object by itself here. It comes after the preposition på:

• på hende = at her

This is similar to English look at her, where at is also required.

Hende means her, so the sentence is referring to the baby as female.

Even though baby is a noun, the pronoun here follows the real-world gender of the person being talked about, not just the grammatical form of the noun.

So:

• hende = her
• ham = him

If the baby were male, you would say:

• Når babyen kaster en legeklods, kigger hunden på ham.

Yes. Kaster is the present tense of kaste.

• at kaste = to throw
• kaster = throws / is throwing

In Danish, the present tense often covers both simple present and present progressive meanings that English separates:

• babyen kaster en legeklods can mean the baby throws a toy block or the baby is throwing a toy block, depending on context.

The same applies to kigger:

• at kigge = to look
• kigger = looks / is looking

A very common way to form the present tense in Danish is to add -r to the infinitive.

• kaste → kaster
• kigge → kigger

So if you know the infinitive, the present tense is often easy to recognize.

Legeklods is a compound noun, which is very common in Danish.

It is made from:

• lege- = related to play
• klods = block

Together, legeklods means something like toy block or building block.

Danish often combines words into one single noun where English might use two words.

Because, as with babyen, Danish usually adds the definite article to the noun itself.

• en hund = a dog
• hunden = the dog

So hunden already includes the meaning of the. You do not need a separate word in front of it.

Yes:

• Hunden kigger på hende, når babyen kaster en legeklods.

This means essentially the same thing.

The main difference is word order:

• If the sentence starts with the subordinate clause, the main clause has inversion: kigger hunden
• If the sentence starts with the main clause, you get normal order: hunden kigger

Both are natural Danish.

Because legeklods is a common-gender noun in Danish, and common-gender nouns take en.

Danish nouns are mainly divided into two genders:

• en-words = common gender
• et-words = neuter

Here:

• en legeklods
• en baby
• en hund

So both baby and hund are also en-words, which is why their definite forms are babyen and hunden.