I skolegården viser læreren min søn, hvor han skal vente i frikvarteret.

This is because Danish is a V2 language in main clauses: the finite verb normally comes in the second position.

So here:

• I skolegården = first element
• viser = second element
• læreren = subject, placed after the verb

If you did not move I skolegården to the front, the sentence would be:

• Læreren viser min søn, hvor han skal vente i frikvarteret.

When you front I skolegården, the verb still has to stay in second position, so the subject moves after it.

In Danish, the definite article is usually attached to the end of the noun.

So:

• skolegård = schoolyard

• skolegården = the schoolyard

• lærer = teacher

• læreren = the teacher

• frikvarter = recess / break
• frikvarteret = the recess / the break

The endings depend on the noun’s gender:

• -en is common with common gender nouns
• -et is common with neuter nouns

Also, Danish often writes compounds as one word, so:

• skolegård = school + yard
• frikvarter is also a single compound noun

Because when a possessive like min, din, hans, vores, etc. comes before the noun, the noun normally stays in its basic indefinite form.

So:

• min søn = my son
  not min sønnen

This is similar to:

• min bog = my book
• vores lærer = our teacher

Danish can also use a postposed possessive:

• sønnen min

But that has a slightly different feel and is often more colloquial or emphatic. For a neutral sentence, min søn is very standard.

Because Danish relies heavily on word order.

In this sentence, after the fronted phrase I skolegården, the finite verb viser comes second, and the subject normally comes right after that:

• I skolegården = fronted adverbial
• viser = finite verb
• læreren = subject
• min søn = object

So the structure is:

• In the schoolyard
  • shows
    • the teacher
      • my son
        • ...

Danish nouns do not show subject/object case the way older English or German can, so position matters a lot.

Because this is an indirect question (or embedded question), not a direct question.

In a direct question, Danish uses question word + verb + subject:

• Hvor skal han vente? = Where should he wait?

But inside a larger sentence, Danish uses subordinate clause word order:

• ..., hvor han skal vente ...

So after hvor, the subject han comes before the verb skal.

That is very common in Danish:

• Jeg ved, hvor han bor.
• Hun spørger, hvad du laver.

Skal here means something like:

• is supposed to
• has to
• should
• sometimes even is to

So hvor han skal vente means not just where he waits in general, but where he is meant to wait or expected to wait.

Also, after a modal verb like skal, Danish uses the infinitive:

• skal vente
• kan komme
• må gå

So vente is in the infinitive because it depends on skal.

In normal context, han will usually be understood as min søn.

That is because the sentence naturally means that the teacher is showing the son where the son should wait during recess.

However, strictly speaking, han could look ambiguous out of context, because both læreren and min søn are masculine singular nouns.

If a speaker wanted to remove all doubt, they might rephrase it, for example:

• I skolegården viser læreren min søn, hvor min søn skal vente i frikvarteret.

That sounds a bit repetitive, though, so the original version is more natural when context makes the reference clear.

Because i is used in Danish for several kinds of location and time expressions.

Here it means:

• I skolegården = in the schoolyard / out in the schoolyard
• i frikvarteret = during recess / at recess

So the same preposition can cover both:

1. physical location
2. time period

This is very normal in Danish:

• i klassen = in the classroom
• i timen = during class
• i pausen = during the break

Danish often uses the definite form for a specific, understood time period in a routine setting.

So i frikvarteret means something like:

• during recess
• during the recess period

It refers to the relevant recess in the school context, so the definite form sounds natural.

This is similar to other common expressions such as:

• i timen = during class
• i pausen = during the break

English often uses no article in these cases, but Danish frequently prefers the definite noun.

Because hvor han skal vente i frikvarteret is a subordinate clause, and the comma marks the boundary before it.

So the sentence is divided like this:

• I skolegården viser læreren min søn,
• hvor han skal vente i frikvarteret.

In Danish, many writers place a comma before a subordinate clause like this. You may also learn that in some comma systems the start comma is optional, so you can sometimes see the same kind of sentence without that comma.

But in teaching materials, putting the comma before hvor is very common and useful because it clearly shows where the subordinate clause begins.