Efter en lang tur tager babyen en lur i barnevognen.

Because babyen means the baby, while en baby means a baby.

In Danish, the definite article is often added to the end of the noun:

• en baby = a baby
• babyen = the baby

The same thing happens with barnevognen:

• en barnevogn = a pram / stroller
• barnevognen = the pram / stroller

The ending -en is the usual definite singular ending for many common-gender nouns in Danish.

So:

• en baby → babyen
• en barnevogn → barnevognen
• en lur → luren

Danish has two grammatical genders:

• common gender: usually takes en
• neuter: usually takes et

For many common-gender nouns, the definite form ends in -en.

Because tur is a common-gender noun, so it takes en, not et.

• en tur = a trip / a walk / an outing

The adjective must match that pattern:

• en lang tur = a long trip/walk

If the noun were neuter, you would often see et and a different adjective form, for example:

• et langt stykke = a long piece

Because tur is a common-gender singular noun with en.

Adjective forms in Danish often work like this:

• en lang tur = common gender singular
• et langt ... = neuter singular
• lange = plural or definite forms in many cases

So:

• en lang tur
• et langt bad
• de lange ture

That is why lang is correct here.

That phrase is a time expression meaning after a long walk/trip. Danish often puts time or place information first in the sentence.

So this part sets the scene:

• Efter en lang tur = After a long walk/trip

It is completely natural in Danish to begin with that kind of phrase.

Because Danish follows the V2 rule in main clauses: the finite verb usually comes in second position.

Here, the first position is the whole phrase:

• Efter en lang tur

So the verb must come next:

• tager

And then the subject follows:

• babyen

So the structure is:

• Efter en lang tur
  • tager
    • babyen
      • ...

This is one of the most important word-order rules in Danish.

Yes. Tage en lur is a normal Danish expression, just like English take a nap.

• tage = to take
• en lur = a nap

So babyen tager en lur means the baby takes a nap / has a nap.

It is idiomatic and very common.

En lur means a nap or a short sleep, usually during the day.

Examples:

• Jeg tager en lur. = I'm taking a nap.
• Barnet fik en lur. = The child had a nap.

It is a very common everyday word, especially when talking about babies and young children.

Because i means in, and the idea is that the baby is napping in the pram/stroller.

• i = in
• barnevognen = the pram/stroller

So:

• i barnevognen = in the pram/stroller

Danish often uses i where English also uses in for being inside something.

Barnevogn is the Danish word for a baby carriage, pram, or stroller, depending on context.

Literally, it is made up of:

• barn/barne- related to child
• vogn = vehicle / carriage / cart

In everyday use, barnevogn usually refers to the thing a baby lies or sits in while being pushed around.

Because the sentence is talking about a specific stroller that is already understood from the situation.

With babies, there is often an obvious stroller/pram involved, so Danish naturally uses the definite form:

• i barnevognen = in the stroller/pram

Using i en barnevogn would mean in a stroller/pram, which sounds less specific.

Yes. Tur is a flexible word in Danish and can mean different things depending on context, such as:

• trip
• walk
• outing
• journey
• sometimes even turn

In Efter en lang tur, it very often means something like after a long walk or after being out for a while.

Yes, very natural.

It sounds like something you might hear in everyday speech or read in simple written Danish, especially in a context about children or daily routines.

The sentence is natural because:

• Efter en lang tur is a normal time-setting phrase
• tager en lur is a common expression
• i barnevognen is exactly the kind of place phrase you would expect with a baby

So the whole sentence is idiomatic and ordinary Danish.