Hun har brug for ro, når hun arbejder hjemmefra.

Because at have brug for is a very common Danish way to say to need.

• Hun har brug for ro = She needs peace/quiet
• Literally, it is closer to She has use for peace/quiet

Danish also has at behøve and at trænge til, which can sometimes translate to need, but have brug for is extremely common and neutral.

Compare:

• Hun har brug for ro = She needs quiet
• Hun behøver ro = She needs quiet
• Hun trænger til ro = She needs/rests for some peace, often with a stronger sense of feeling worn out or craving it

So in this sentence, har brug for is just a very natural everyday choice.

In the fixed expression at have brug for, the noun brug appears without an article. That is simply how the idiom works.

So you learn it as a chunk:

• at have brug for noget = to need something
• at have brug for nogen = to need someone

Examples:

• Jeg har brug for hjælp = I need help
• Vi har brug for mere tid = We need more time

Even though brug is a noun in other contexts, in this expression you should think of har brug for as one unit.

Ro usually means calm, peace, quiet, or peace and quiet, depending on context.

In this sentence, ro most naturally means something like:

• quiet
• peace and quiet
• calm surroundings

It does not necessarily mean complete silence. It is broader than that.

For example:

• Jeg har brug for ro = I need some peace and quiet
• Der er ro i huset = The house is calm/quiet

So ro is a very natural word here if someone needs undisturbed working conditions at home.

Because ro is being used as an uncountable noun, like peace, quiet, or calm in English.

Danish often leaves out the article with abstract or mass nouns:

• Hun har brug for ro = She needs quiet
• Jeg vil have fred = I want peace
• Vi mangler tid = We lack time

You would not normally say en ro here.

This is a very common question.

• ro = calm, peace, quiet, lack of disturbance
• stilhed = silence

So:

• Hun har brug for ro means she needs calm/peace and quiet
• Hun har brug for stilhed means she needs actual silence

If someone is working from home, ro is often the better word because it suggests not being disturbed, not necessarily total silence.

Because når is used for when in the sense of something that happens regularly, generally, or whenever.

Here the meaning is:

• when she works from home
• or more naturally, whenever she works from home

That is why når fits.

Compare:

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

Examples:

• Når hun arbejder hjemmefra, har hun brug for ro = When/whenever she works from home, she needs quiet
• Da hun arbejdede hjemmefra i sidste uge, havde hun brug for ro = When she worked from home last week, she needed quiet
• Hvis hun arbejder hjemmefra i morgen, har hun brug for ro = If she works from home tomorrow, she needs quiet

Because the sentence expresses a general fact or a habitual situation.

It means something like:

• She needs quiet when she works from home
• Whenever she works from home, she needs quiet

In Danish, the present tense is often used for general truths and repeated actions, just as in English.

If you wanted to talk about the past, you would change both:

• Hun havde brug for ro, når hun arbejdede hjemmefra = She needed quiet when she worked from home

Hjemmefra means from home.

So:

• arbejder hjemmefra = works from home

It is commonly used in modern Danish for remote work.

Examples:

• Jeg arbejder hjemmefra i dag = I’m working from home today
• Hun studerer hjemmefra = She studies from home

It is often written as one word: hjemmefra.

They are similar, but not exactly the same.

• arbejder hjemmefra = works from home, especially in the remote-work sense
• arbejder hjemme = works at home / is working at home

hjemmefra emphasizes that home is the base or location you are working from instead of going elsewhere, such as an office.

So in a sentence about remote work, arbejder hjemmefra is especially natural.

Because når hun arbejder hjemmefra is a subordinate clause, and Danish word order changes in subordinate clauses.

In a normal main clause, Danish typically has the finite verb in second position:

• Hun arbejder hjemmefra = She works from home

But after a subordinating conjunction like når, the clause usually keeps subject + verb order:

• når hun arbejder hjemmefra = when she works from home

So:

• main clause: Hun arbejder hjemmefra
• subordinate clause: når hun arbejder hjemmefra

This is a very important pattern in Danish.

Because når hun arbejder hjemmefra is a subordinate clause, and Danish normally uses a comma before subordinate clauses.

So:

• Hun har brug for ro, når hun arbejder hjemmefra.

This comma is standard in Danish writing.

English is sometimes less consistent about such commas, but in Danish this is very normal.

Yes, absolutely. That is also correct.

Both versions mean the same thing:

• Hun har brug for ro, når hun arbejder hjemmefra.
• Når hun arbejder hjemmefra, har hun brug for ro.

The difference is mostly about focus and style.

Notice the word order in the main clause after the fronted subordinate clause:

• Når hun arbejder hjemmefra, har hun brug for ro
• not Når hun arbejder hjemmefra, hun har brug for ro

This happens because Danish main clauses still require the finite verb in second position.

Yes, that is grammatically correct and natural.

• Hun har brug for ro = She needs quiet
• Hun behøver ro = She needs quiet

Both work.
However, har brug for often sounds slightly more everyday and idiomatic in many contexts.

So if you learn one very safe, common version, har brug for is an excellent choice.

A careful approximate pronunciation is:

hoon har broo for ro, nor hoon ar-bye-der yem-me-fra

A few useful notes:

• Hun sounds roughly like hoon, but with a Danish vowel quality
• brug has a long u sound
• for is often pronounced more weakly in normal speech
• ro has a long vowel
• når sounds roughly like nor
• arbejder is often pronounced more like AR-bye-der than the spelling suggests
• hjemmefra is YEM-me-fra, with hj sounding like a y sound

As in all Danish, actual spoken pronunciation is usually softer and more reduced than the spelling suggests.