Jeg arbejder effektivt, når der er ro i rummet.

Because effektivt is functioning as an adverb here: it describes how the speaker works.

• effektiv = the basic adjective form
• effektivt = the form often used adverbially, similar to English effectively or efficiently

So:

• et effektivt system = an efficient system
• Jeg arbejder effektivt = I work efficiently / effectively

In this sentence, it modifies the verb arbejder, not a noun.

Here, når means when or whenever.

It is used for something that happens generally, repeatedly, or under a certain condition:

• Jeg arbejder effektivt, når der er ro i rummet. = I work efficiently when/whenever there is quiet in the room.

This is different from a one-time past event, where Danish often uses da instead.

A useful contrast:

• når = when / whenever, in general or in the future
• da = when, about a specific past occasion

der er is the normal Danish way to say there is or there are in an existential sense.

So:

• der er ro = there is quiet
• der er en bog på bordet = there is a book on the table

The der here does not mean a specific place like English there in over there. It is a grammatical word used to introduce existence.

So når der er ro i rummet literally means something like:

• when there is quiet in the room

Because ro is an uncountable or abstract noun here, meaning quiet, peace, or calm.

In English, we also usually say:

• there is quiet
• there is peace
• not usually there is a quiet

So in Danish:

• der er ro = there is quiet / it is quiet
• ro is being used in a general, non-countable sense

You will often see this with abstract nouns in Danish.

ro means quiet, calm, or peace.

In this sentence, the best natural sense is probably quiet or calm in the room. It suggests an environment without noise or disturbance.

So der er ro i rummet means more than just it is silent. It can also imply:

• no interruptions
• a calm atmosphere
• a peaceful working environment

That is why ro is a very natural word here.

rummet means the room.

The base noun is:

• et rum = a room

Danish usually adds the definite article to the end of the noun:

• rum = room
• rummet = the room

So:

• i rummet = in the room

This is one of the big differences from English. Instead of a separate word like the, Danish often attaches definiteness directly to the noun.

Because this is a subordinate clause, introduced by når.

In main clauses, Danish usually follows the V2 rule, where the finite verb comes in second position:

• Jeg arbejder effektivt.

But after a subordinating conjunction like når, Danish does not use main-clause V2 word order. Instead, the clause keeps a more regular subordinate structure:

• når der er ro i rummet

So the order is:

• når
  • der
    • er
      • ro
        • i rummet

That is normal and correct Danish subordinate-clause order.

Yes, absolutely.

You can say:

• Når der er ro i rummet, arbejder jeg effektivt.

This means the same thing, but now the time/condition clause comes first.

When a subordinate clause comes first in Danish, the main clause usually shows inversion:

• not Når der er ro i rummet, jeg arbejder effektivt
• but Når der er ro i rummet, arbejder jeg effektivt

So after the fronted clause, the verb arbejder comes before the subject jeg.

It can mean either, depending on context.

Danish present tense often covers both:

• I work
• I am working

So:

• Jeg arbejder effektivt can mean I work efficiently in general
• or I am working efficiently if the context is about what is happening now

In this sentence, because of når and the general idea of a condition, it most naturally sounds like a general statement:

• I work efficiently when the room is quiet.

Yes, but the wording would change.

You could say:

• når der er stille i rummet = when it is quiet in the room

That is also natural Danish.

The difference is:

• ro is a noun: quiet, calm, peace
• stille is an adjective: quiet, still

So:

• der er ro i rummet = there is calm/quiet in the room
• det er stille i rummet = it is quiet in the room

Both are possible, but der er ro has a slightly stronger sense of calmness and lack of disturbance.

Usually yes, in a sentence like this.

• i = in
• rummet = the room

So i rummet = in the room

Depending on context, English might sometimes say in the room or around the room, but the direct meaning is simply in the room. Here it tells you where the quietness is.

It is really both.

The sentence states a general pattern:

• Jeg arbejder effektivt = I work efficiently
• når der er ro i rummet = when there is quiet in the room

So it describes:

1. a habitual/general truth about the speaker
2. a condition under which that happens

A natural English explanation would be:

• I tend to work efficiently when the room is quiet.

That is exactly the kind of meaning når often helps express in Danish.