Læreren skriver overskriften på tavlen.

Because Danish usually puts the definite article on the end of the noun instead of using a separate word like English the.

• lærer → læreren
• overskrift → overskriften
• tavle → tavlen

So that -en ending here means the.

It depends on the noun’s gender.

• Common gender nouns usually take -en
• Neuter nouns usually take -et

In this sentence, all three nouns are common gender:

• en lærer
• en overskrift
• en tavle

So their definite forms are:

• læreren
• overskriften
• tavlen

The parts are:

• Læreren = the subject
• skriver = the verb
• overskriften = the direct object
• på tavlen = a prepositional phrase telling you where the action happens

A common English-speaker mistake is to think tavlen is the object, but it is not. The thing being written is overskriften. På tavlen only tells you the location.

skriver is the present tense of skrive.

A very common pattern in Danish is:

• infinitive: skrive
• present tense: skriver

In English, this can correspond to either:

• writes
• is writing

Danish often uses the same present form for both, and the context tells you which meaning is intended.

Because Danish verbs are much simpler than English verbs in this way: they do not change for person.

So you get:

• jeg skriver
• du skriver
• han skriver
• vi skriver

The verb stays skriver for all of them.

This is the normal word order for a simple main clause:

• subject
  • verb
    • object
      • other information

So:

• Læreren = subject
• skriver = verb
• overskriften = object
• på tavlen = place

But the deeper Danish rule is that the finite verb must be in second position in a main clause. That is called V2 word order.

For example, you could also say:

• På tavlen skriver læreren overskriften.

Here på tavlen comes first, but skriver is still the second element.

på is used because the writing appears on the surface of the board.

That matches English quite closely:

• on the board → på tavlen

If you used i, that would suggest in/inside something, which does not fit here.

Because in normal Danish, a definite noun usually takes the suffix article by itself:

• læreren
• tavlen

You do not normally add a separate the-word as well.

A separate word like den/det/de is used in other situations, especially:

1. With an adjective

   • den gode lærer
   • den store tavle

2. As a demonstrative, more like that

   • den tavle = that board

So for a simple definite noun, Danish prefers the ending:

• læreren, not den læreren

The æ sound is one that English speakers often need to practice. It is somewhat like the vowel in cat for many learners, though it is not exactly the same.

A rough learner-friendly pronunciation of læreren is something like:

• LAIR-er-en or LEH-rer-en

But that is only approximate. The real Danish sound is a bit different, and pronunciation varies somewhat by accent.

Two useful points:

• æ is a real vowel sound, not something you say as separate letters
• the ending -eren is usually spoken quite smoothly, not heavily separated syllable by syllable

Because the sentence is talking about specific things already understood in the situation:

• the teacher
• the heading
• the board

That is very natural in classroom-style descriptions. Danish, like English, often uses definite forms when the speaker and listener can identify the thing being talked about from the context.