Om kvelden drikker hun kakao i stedet for kaffe.

Because Norwegian often puts a time expression first when it sets the scene for the rest of the sentence.

So Om kvelden drikker hun kakao ... is very natural and means something like In the evening, she drinks cocoa ...

You could also say:

Hun drikker kakao i stedet for kaffe om kvelden.

That is also correct, but it sounds a little less fronted and less focused on the time.

In Norwegian, moving a time phrase to the front is very common.

In Norwegian, om kvelden is a common fixed expression for in the evening / during the evening / in the evenings.

The preposition om is often used with parts of the day in general or repeated-time expressions:

• om morgenen = in the morning
• om dagen = during the day / in the daytime
• om kvelden = in the evening
• om natten = at night

So this is something you mostly learn as a standard pattern.

I kvelden is not the normal way to say this in standard Norwegian.

Norwegian often uses the definite form in these time expressions.

So:

• kveld = evening
• kvelden = the evening

Even though it literally looks like the evening, the whole phrase om kvelden is idiomatic and usually just means in the evening.

This is very common in Norwegian. English and Norwegian do not always use articles the same way.

Because Norwegian is a V2 language. That means the finite verb usually comes in the second position in main clauses.

Here, the first element is:

Om kvelden

So the verb must come next:

Om kvelden drikker hun ...

Structure:

• 1st position: Om kvelden
• 2nd position: drikker
• then subject: hun

This is why Om kvelden hun drikker ... is wrong in a normal main clause.

Yes, absolutely.

That version is grammatical and natural. The difference is mainly focus:

• Om kvelden drikker hun kakao i stedet for kaffe.
  Focuses first on the time.
• Hun drikker kakao i stedet for kaffe om kvelden.
  Starts with the subject and sounds more neutral.

Both are good Norwegian.

Drikker is the present tense of å drikke = to drink.

Here it is used for a general habit or usual action, just like English often uses the present tense for routines:

• Hun drikker kaffe om morgenen.
• Hun drikker kakao om kvelden.

So it does not have to mean she is drinking it right now. It can describe what she generally does.

Because Norwegian often leaves out the article with uncountable nouns or when speaking about something in a general sense.

So:

• drikker kakao = drinks cocoa / hot chocolate
• drikker kaffe = drinks coffee

This works much like English, where you also usually say drink coffee, not drink a coffee, unless you mean one serving in a specific context.

If you wanted to be more specific, you could add an article or another determiner in some situations, but in this sentence the bare nouns are the normal choice.

I stedet for means instead of.

It introduces the thing being replaced:

• kakao i stedet for kaffe = cocoa instead of coffee

This is a very useful expression in Norwegian.

Examples:

• Jeg tar te i stedet for kaffe. = I’ll have tea instead of coffee.
• Hun gikk i stedet for å kjøre. = She walked instead of driving.

So in your sentence, kaffe is the thing she is choosing not to have.

Yes. In many contexts, you may see both:

• i stedet for
• istedenfor

Both are used, though i stedet for is often presented as the clearer, more transparent form for learners because you can easily see the parts.

In your sentence, i stedet for kaffe is completely standard.

It can often suggest a habitual meaning, especially with the present tense.

So in this sentence, many learners would naturally understand it as something like:

• In the evening, she drinks cocoa instead of coffee
• or more idiomatically in English: In the evenings, she drinks cocoa instead of coffee

The exact English translation depends on context, but the Norwegian is very commonly used for repeated habits.

In everyday Norwegian, kakao often refers to the drink that English speakers might call hot chocolate or cocoa, depending on context.

So although the exact word choice in English can vary, kakao in an everyday sentence like this usually means the warm chocolate drink, not just cocoa powder as an ingredient.

A simple breakdown is:

• Om kvelden = time expression
• drikker = finite verb
• hun = subject
• kakao = object
• i stedet for kaffe = prepositional phrase meaning instead of coffee

So the overall pattern is:

Time + Verb + Subject + Object + Prepositional phrase

This is a very common Norwegian main-clause pattern when something other than the subject comes first.