Fortælleren beskriver bipersonen.

In both words, -en is the definite article attached to the noun.

So:

• en fortæller = a narrator
• fortælleren = the narrator

and:

• en biperson = a supporting character / secondary character
• bipersonen = the supporting character

Unlike English, Danish often puts the at the end of the noun instead of using a separate word.

Because Danish usually expresses definiteness by adding it to the noun itself.

So instead of saying something like the narrator, Danish says:

• fortælleren

And instead of the supporting character, it says:

• bipersonen

This is very normal in Danish. A separate definite word like den is usually only added in certain constructions, for example with an adjective:

• bipersonen = the supporting character
• den vigtige biperson = the important supporting character

Beskriver is the present tense of the verb beskrive (to describe).

So:

• at beskrive = to describe
• beskriver = describes / is describing

In Danish, the present tense is often formed by adding -r to the infinitive:

• at tale → taler
• at skrive → skriver
• at beskrive → beskriver

In this sentence, the word order tells you that:

• Fortælleren = subject
• beskriver = verb
• bipersonen = object

So the basic pattern is:

Subject + Verb + Object

That is the normal order in a simple Danish main clause.

Even though both nouns end in -en, they do not have special subject/object endings. You understand their role mainly from position in the sentence.

Fortæller comes from the verb fortælle (to tell). It can mean teller in a broad sense, but in literary contexts it usually means narrator.

So in a sentence about literature, stories, or analysis, fortælleren is most naturally understood as:

• the narrator

Context matters, but here narrator is definitely the right interpretation.

Biperson means something like:

• supporting character
• secondary character
• minor character

It is a compound noun, which is very common in Danish. Danish often joins words together where English uses two separate words.

Here:

• bi- = secondary / side-
• person = person / character

So biperson is literally something like side-person, but the natural English meaning is supporting character or secondary character.

Because both nouns are common gender nouns in Danish.

Danish has two grammatical genders:

• common gender → takes en
• neuter gender → takes et

These two nouns are common gender:

• en fortæller
• en biperson

That is why their definite forms are:

• fortælleren
• bipersonen

A neuter noun would usually have -et in the definite singular instead.

A rough English-friendly pronunciation might be:

for-TEL-er-en beh-SKRY-ver BEE-per-so-nen

A few helpful notes:

• æ in fortælleren is a front vowel, somewhat like the vowel in cat, but not exactly the same.
• skri in beskriver is pronounced more like skree.
• The r sounds in Danish are softer and more back in the mouth than in most English accents.
• Final syllables like -en are often pronounced quite lightly.

A more approximate IPA version would be something like:

[fɒˈtɛlɐn bəˈsgʁiːvɐ biˈpʰɛɐ̯soːnən]

Exact pronunciation varies a bit by speaker and region.

Yes. Danish present tense often covers both meanings, depending on context.

So:

• Fortælleren beskriver bipersonen.

can mean:

• The narrator describes the supporting character.
• The narrator is describing the supporting character.

Danish does not use a continuous -ing form in the same way English does. The present tense often does both jobs.

Yes, but Danish main clauses follow the verb-second rule, often called V2.

The neutral sentence is:

• Fortælleren beskriver bipersonen.

If you move another element to the front, the verb still stays in second position. For example:

• Bipersonen beskriver fortælleren.
  Now the meaning changes: The supporting character describes the narrator.

Or with an adverbial:

• I romanen beskriver fortælleren bipersonen.
  In the novel, the narrator describes the supporting character.

So word order matters a lot in Danish.

Because Danish does not capitalize all nouns.

Unlike German, Danish capitalization is much closer to English:

• capitalize the first word of the sentence
• capitalize proper nouns
• do not capitalize ordinary nouns

So:

• Fortælleren beskriver bipersonen. ✅
• Fortælleren beskriver Bipersonen. ❌

unless Bipersonen were somehow part of a title or name.

It is a very standard Danish sentence. It shows several very common patterns all at once:

• definite nouns with endings: fortælleren, bipersonen
• present tense verb: beskriver
• normal main-clause word order: Subject + Verb + Object

So it is a good model sentence for basic Danish structure.