Hvis et myggebid gør meget ondt, lægger min søster et koldt håndklæde på armen.

Hvis introduces a condition, like English if.

So Hvis et myggebid gør meget ondt means if a mosquito bite hurts a lot. In Danish, this whole hvis-clause is a subordinate clause that sets up the situation before the main clause.

In some contexts, hvis can feel close to when in English, especially in general statements, but grammatically it is still the normal word for if.

Danish, like German, very often makes compound nouns by joining words together.

• myg = mosquito
• bid = bite

Together they become myggebid = mosquito bite.

The extra -e- in the middle is a linking sound that often appears in compounds. You just have to learn these as part of the word.

This is very normal in Danish:

• håndklæde = towel
• sommerferie = summer holiday
• skolelærer = school teacher

Both myggebid and håndklæde are neuter nouns in Danish, so they take et as the indefinite article.

• et myggebid
• et håndklæde

When an adjective describes a neuter singular noun, it usually gets -t:

• kold = cold
• et koldt håndklæde = a cold towel

So the -t in koldt matches the neuter noun håndklæde.

Gøre ondt is a very common Danish expression meaning to hurt or to cause pain.

Literally:

• gør = does/makes
• ondt = painfully / sorely

But you should learn gøre ondt as a fixed expression:

• Det gør ondt = It hurts
• Min arm gør ondt = My arm hurts

Danish does have words related to pain, but gøre ondt is the everyday, natural way to say that something hurts.

Ondt is the form used in the expression gøre ondt.

It comes from ond, but in this expression it works idiomatically, so it is best not to translate it word-for-word. Just think of:

• gøre ondt = hurt

You will see this same form in other common patterns:

• Det gør ondt
• Hvor gør det ondt?
• Det gjorde rigtig ondt

So even though ond by itself can mean something like bad, evil, or painful depending on context, ondt here is part of the set phrase.

Meget means very, much, or a lot, depending on context.

In gør meget ondt, it intensifies the pain:

• gør ondt = hurts
• gør meget ondt = hurts a lot / hurts very much

This word order is normal:

• Det gør meget ondt
• Det gør lidt ondt
• Det gør virkelig ondt

So meget is modifying the whole idea of how much it hurts.

This is a very important Danish word-order rule.

Danish main clauses normally have the finite verb in second position. This is called the V2 rule.

Here, the sentence begins with a subordinate hvis-clause:

• Hvis et myggebid gør meget ondt

Because that whole clause comes first, the main clause must start with the verb:

• lægger min søster et koldt håndklæde på armen

So the structure is:

1. fronted element: Hvis et myggebid gør meget ondt
2. finite verb: lægger
3. subject: min søster

Compare:

• Min søster lægger et koldt håndklæde på armen.
• Hvis et myggebid gør meget ondt, lægger min søster et koldt håndklæde på armen.

That inversion is completely normal in Danish.

Lægger is the present tense of lægge, which means to lay or to put down, especially something that is placed flat or horizontally.

A towel is something you typically lay on an arm, so lægge is a natural choice.

Danish often chooses different placement verbs depending on the shape or position of the object:

• lægge = lay something down
• stille = set something standing
• sætte = set something sitting / place in position
• putte = put something in/into

So lægger et koldt håndklæde på armen sounds natural because the towel is being laid onto the arm.

The present tense is used here for a general or habitual situation.

The sentence is not talking about one specific past event. It means something like:

• whenever this happens, this is what my sister does

So Danish uses the present tense naturally, just as English can:

• If a mosquito bite hurts a lot, my sister puts a cold towel on the arm.

If you wanted a past event, you would use a past tense form instead:

• lagde = laid / put

Danish often uses the definite form with body parts when the owner is obvious from the context.

So:

• på armen = on the arm

This is very natural when everyone understands whose arm is meant. English often prefers a possessive, but Danish often does not need one.

Compare:

• Han vasker hænderne = He washes his hands
• Hun slog sig i hovedet = She hit her head
• Hun lægger et koldt håndklæde på armen = She puts a cold towel on the arm / on the arm in question

If you wanted to emphasize ownership, you could say på sin arm or på hendes arm, but that is not necessary here.

Because the sentence begins with a subordinate clause and then moves to the main clause.

• Hvis et myggebid gør meget ondt, = subordinate clause
• lægger min søster et koldt håndklæde på armen. = main clause

In standard Danish writing, a comma is normally placed between those two parts.

So the comma helps show the structure of the sentence:

• condition first
• main statement second