Den blå kjole er pæn.

Because kjole is a common-gender noun in Danish, and common-gender nouns take den in the definite form.

• en kjole = a dress
• den blå kjole = the blue dress

If the noun were neuter, you would use det instead:

• et hus = a house
• det blå hus = the blue house

So the article depends on the noun’s gender, not on the English translation.

This is a very common question.

In Danish, when a noun has an adjective before it and is definite, you normally use:

• den/det/de + adjective + noun

So you say:

• den blå kjole

not:

• den blå kjolen

Compare:

• kjolen = the dress
• den blå kjole = the blue dress

So Danish usually does not keep the -en/-et ending on the noun when there is a definite article before an adjective.

Because blå is one of the adjectives that often stays blå in this kind of form.

Compare:

• en blå kjole = a blue dress
• den blå kjole = the blue dress
• de blå kjoler = the blue dresses

But in neuter singular indefinite, it becomes:

• et blåt bælte = a blue belt

So blå can change to blåt, but in den blå kjole, blå is the correct form.

Because pæn agrees with kjole, which is common gender singular.

Predicate adjectives after er agree like this:

• common singular: pæn
• neuter singular: pænt
• plural: pæne

Examples:

• Kjolen er pæn. = The dress is pretty/nice.
• Huset er pænt. = The house is pretty/nice.
• Kjolerne er pæne. = The dresses are pretty/nice.

Even though den blå kjole is definite, the adjective after er does not become a definite form. It just agrees for gender and number.

They are both adjectives, but they do different jobs.

• blå is an attributive adjective: it comes before the noun and describes it directly.
  • den blå kjole
• pæn is a predicative adjective: it comes after the verb er.
  • kjolen er pæn

So in this sentence:

• den blå kjole = the blue dress
• er pæn = is pretty/nice

This is the same basic pattern as in English:

• the blue dress
• is pretty

Here, den means the.

In Danish, den/det/de can sometimes also be used in a more demonstrative sense, like that/those, depending on stress and context. But in a normal sentence like:

• Den blå kjole er pæn.

the most natural reading is simply:

• The blue dress is pretty.

So here den is just the definite article used before an adjective.

Roughly, kjole sounds like SHO-luh.

A few helpful points:

• The kj is not pronounced like English k + j.
• In modern Danish, it is usually a soft sound somewhat like sh.
• The o is long.
• The final -e is a weak uh sound.

So an English-friendly approximation is:

• kjole ≈ SHO-luh

It will not sound exactly like English, but that is a good starting point.

The æ in Danish is a very common vowel, and in pæn it is pronounced somewhat like the e in bed, but usually longer and tenser than in English.

A rough approximation:

• pæn ≈ pehn

A few notes:

• p is straightforward.
• æ is the important part: it is not like English ay.
• The word may also have a slight Danish stød depending on pronunciation, but beginners do not need to master that immediately.

If you aim for something close to pehn, you will be understood.

Not exactly.

Pæn often means:

• pretty
• nice-looking
• neat
• sometimes even smart or presentable

For clothes, pæn can mean the dress looks nice or attractive, but it can also suggest that it looks tidy or suitable.

A stronger word is smuk, which is closer to:

• beautiful
• gorgeous

So:

• Den blå kjole er pæn. = The blue dress is pretty/nice.
• Den blå kjole er smuk. = The blue dress is beautiful.

Yes. That means:

• The dress is blue.

The difference is structure and focus:

• Den blå kjole er pæn. = The blue dress is pretty.
  • Here blue helps identify which dress.
• Kjolen er blå. = The dress is blue.
  • Here blue is the new information about the dress.

So Danish can use the adjective either:

• before the noun: den blå kjole
• after the verb: kjolen er blå

Both are correct, but they mean slightly different things.