Den blå skjorte passer godt til de sorte bukser.

Because den is used for a singular common-gender noun, while de is used for plural nouns.

• skjorte = shirt, singular
• bukser = trousers/pants, plural

So:

• den blå skjorte = the blue shirt
• de sorte bukser = the black trousers

In Danish, den and det are singular definite articles, and de is the plural definite article.

Because skjorte is a common-gender noun in Danish, not a neuter noun.

Danish nouns have two genders:

• common gender → takes en in the indefinite form and den in the definite phrase
• neuter → takes et in the indefinite form and det in the definite phrase

Since it is:

• en skjorte = a shirt

the definite phrase becomes:

• den blå skjorte = the blue shirt

If it were a neuter noun, you would use det instead.

This is because these two adjectives behave differently.

blå is an adjective whose forms are:

• common singular: blå
• neuter singular: blåt
• plural/definite: blå

So in den blå skjorte, blå stays blå.

sort has these forms:

• common singular: sort
• neuter singular: sort
• plural/definite: sorte

So in de sorte bukser, the adjective takes the -e form.

This is something learners usually just have to get used to: not all Danish adjectives change in exactly the same way.

Because bukser is plural, and with plural definite noun phrases Danish uses the plural/definite adjective form.

So:

• en sort skjorte = a black shirt
• de sorte bukser = the black trousers

The -e ending on sorte shows that the adjective is agreeing with a plural or definite noun phrase.

Because when a noun has a preceding adjective, Danish normally uses den/de/det plus the adjective, and the noun usually stays in its basic form.

Compare:

• skjorten = the shirt
• den blå skjorte = the blue shirt

And:

• bukserne = the trousers
• de sorte bukser = the black trousers

So you do not normally say den blå skjorten here.

passer til means something like:

• goes with
• matches
• suits

And godt means well.

So passer godt til means:

• goes well with
• matches well with

It is a very common way to talk about clothes, colors, furniture, styles, and things that look good together.

Because the verb expression is passe til, which means to go with / to match.

So the pattern is:

• X passer til Y = X goes with Y

In this sentence:

• Den blå skjorte passer godt til de sorte bukser.
• The blue shirt goes well with the black trousers.

You should learn passer til as a set expression.

Yes. Passe can mean different things depending on context.

Common meanings include:

• to fit
• to suit
• to match / go with

For example:

• Skjorten passer mig. = The shirt fits me.
• Det passer godt. = That suits/is fine.
• Den blå skjorte passer til bukserne. = The blue shirt goes with the trousers.

So in this sentence, the meaning is clearly matches/goes well with, not physically fits.

Yes, very similar. Bukser is normally used as a plural noun, just like trousers in English.

So:

• et par bukser = a pair of trousers/pants
• de sorte bukser = the black trousers/the black pants

Even when you mean one item of clothing, Danish usually still uses the plural form bukser.

Passer is the present tense form of passe.

Danish present tense is usually made with -r or -er, and it does not change according to the subject the way English does in some cases.

So:

• jeg passer
• du passer
• den passer
• vi passer

In this sentence:

• skjorte is the subject
• the verb is in the present tense: passer

So the sentence means that the shirt goes well with the trousers now/in general.

Yes. That is perfectly correct.

It would mean:

• The black trousers go well with the blue shirt.

The basic meaning stays the same. The difference is mostly what you choose to focus on first.

So both are natural:

• Den blå skjorte passer godt til de sorte bukser.
• De sorte bukser passer godt til den blå skjorte.

No. Here godt is functioning as an adverb, meaning well.

Compare:

• en god skjorte = a good shirt
  Here god is an adjective describing a noun.

• passer godt til = goes well with
  Here godt modifies the verb phrase, so it is acting like an adverb.

This is why the sentence means matches well, not matches a good something.

Yes.

• Den blå skjorte passer til de sorte bukser.
  = The blue shirt goes with the black trousers.

Adding godt makes it stronger and more natural in many situations:

• passer til = goes with
• passer godt til = goes well with

So godt adds the idea that the match is especially good.

Yes, the j is part of the pronunciation.

A rough English-friendly approximation of skjorte is something like:

• SHOR-tuh

But Danish pronunciation is softer and more compressed than that.

A few helpful points:

• skj at the beginning sounds roughly like sh
• or is not exactly like English or, but that approximation is useful at first
• the final -e is a weak vowel, like a very light uh

So an English speaker can start by thinking SHOR-tuh, while knowing the real Danish sound is subtler.

Because this is a straightforward main clause, and Danish often uses the same basic order as English in simple statements:

• Subject + verb + adverb + prepositional phrase

Here that is:

• Den blå skjorte = subject
• passer = verb
• godt = adverb
• til de sorte bukser = prepositional phrase

So the structure is very close to English:

• The blue shirt goes well with the black trousers.

That is one reason this sentence feels fairly easy for English speakers.