Brandalarmen lyder, når vi bruger alarmtrykket.

In Danish, the definite article is usually added to the end of the noun instead of being a separate word.

• brandalarm = fire alarm
• brandalarmen = the fire alarm

So -en here means the.
This is very common in Danish:

• bil = car
• bilen = the car

Since brandalarm is a common-gender noun, it takes -en in the definite singular.

Here, lyder means sounds or goes off.

The verb is at lyde, which can mean:

• to sound
• to ring
• to make a noise

So Brandalarmen lyder means that the fire alarm is making its warning sound.

This is a good example of how Danish often uses a simple verb where English might use a short phrase like goes off.

Danish often uses the present tense for general truths, instructions, and things that happen whenever something else happens.

So Brandalarmen lyder, når vi bruger alarmtrykket means something like:

• The fire alarm sounds when we use the alarm button
• The fire alarm goes off when we use the alarm button

It is not limited to something happening right now. It describes a normal result or rule.

English does this too:

• Water boils at 100 degrees.
• The light turns on when you press the switch.

Når usually means when in the sense of:

• when(ever)
• at the time that
• whenever this happens

In this sentence, it introduces the condition under which the alarm sounds:

• når vi bruger alarmtrykket = when we use the alarm button

For many learners, the important contrast is:

• når = when / whenever
• hvis = if

Here når is natural because the sentence describes what happens in that situation as a normal consequence.

Sometimes Danish can use both, but they are not exactly the same.

• når suggests when/whenever this happens
• hvis suggests if this happens

In this sentence, når sounds more like a factual instruction or general rule: whenever the alarm button is used, the fire alarm sounds.

If you said hvis vi bruger alarmtrykket, it would sound a bit more hypothetical: if we use the alarm button, then the fire alarm will sound.

So når is the more natural choice here.

Alarmtrykket is a compound noun.

It is made from:

• alarm = alarm
• tryk = press / push / button / pressure, depending on context

In this sentence, alarmtrykket refers to the alarm push button or alarm call point.

The ending -et makes it definite:

• alarmtryk = alarm button / alarm press point
• alarmtrykket = the alarm button / the alarm call point

Danish forms many words this way by joining nouns together into one word.

Because Danish nouns belong to different grammatical genders.

Very roughly:

• common gender nouns usually take -en in the definite singular
• neuter nouns usually take -et in the definite singular

So here:

• brandalarm → brandalarmen
• alarmtryk → alarmtrykket

You often just have to learn the gender of each noun along with the word itself.

Because når vi bruger alarmtrykket is a subordinate clause, and Danish normally places a comma before subordinate clauses.

So the structure is:

• main clause: Brandalarmen lyder
• subordinate clause: når vi bruger alarmtrykket

This is standard Danish punctuation.

Yes. After når, you get subordinate clause word order.

Here the clause is:

• når vi bruger alarmtrykket

This has the normal subordinate order:

• conjunction: når
• subject: vi
• verb: bruger
• object: alarmtrykket

That is different from the kind of inversion you often see in main clauses in Danish.

For example, in a main clause you might get:

• Nu bruger vi alarmtrykket

But after når, Danish keeps the subject before the verb:

• når vi bruger alarmtrykket

It literally means we, but in contexts like instructions or explanations, it can be used a bit more generally.

Depending on context, vi may mean:

• we
• we people here
• we as users
• we in general

So in a practical instruction, vi may sound less personal than English we and can simply describe what happens when people use the alarm button.

A rough guide is LYU-thur or LYU-der, but the real Danish pronunciation is softer than English spelling suggests.

A few helpful points:

• y is a rounded vowel that English does not really have
• the d in lyder is usually a soft Danish d, not a hard English d
• the -er ending is often reduced

So don’t expect it to sound exactly like the spelling. The most important thing at first is to recognize it as the present tense of at lyde.

Not very naturally.

A very literal translation would be something like:

• The fire alarm sounds, when we use the alarm button.

That is understandable, but more natural English would be:

• The fire alarm sounds when we use the alarm button.
• The fire alarm goes off when we use the alarm button.

This is a good reminder that Danish and English often match closely in structure, but the most natural wording is not always word-for-word.