Lukten gjør henne kvalm.

Lukten is the definite form of the noun, so it means the smell.

• lukt = smell / a smell
• lukten = the smell

Norwegian often puts definiteness at the end of the noun, so there is no separate word like English the here.

Not exactly. The verb gjøre often does mean do, but in this pattern it means make or cause.

The pattern is:

gjøre + someone + adjective

So:

• gjør henne kvalm = makes her nauseous

A couple of similar examples:

• Det gjør meg glad. = It makes me happy.
• Det gjør ham sint. = It makes him angry.

So this is a very common Norwegian structure.

Because henne is the object form of hun.

• hun = she (subject)
• henne = her (object)

In this sentence, the smell is doing something to her, so her is the object:

• Lukten gjør henne kvalm.

Compare:

• Hun er kvalm. = She is nauseous.
• Lukten gjør henne kvalm. = The smell makes her nauseous.

Kvalm is an adjective meaning nauseous, queasy, sick to the stomach.

In this sentence, it describes the state that henne ends up in because of the smell. So grammatically, it works like an object complement:

• Lukten = subject
• gjør = verb
• henne = object
• kvalm = adjective describing the object

So Norwegian is literally saying something like:

The smell makes her nauseous.

Because it is referring to henne, which is singular and not neuter. In that situation, the basic adjective form is used: kvalm.

You can compare:

• gjør henne kvalm = singular
• gjør dem kvalme = plural

So the form kvalm is exactly what you would expect here.

Yes. Lukten is the subject, because it is the thing causing the effect.

The sentence structure is:

Lukten + gjør + henne + kvalm
subject + verb + object + complement

This is fairly close to English word order, which is one reason this sentence is easier to understand once you know the forms.

Yes. Many learners will also come across lukta.

In Bokmål, some nouns can appear with different definite forms depending on style and gender choice. So you may see or hear both:

• lukten
• lukta

Both can mean the smell.
Lukten may feel a bit more neutral or standard in many textbooks, while lukta is also very common in everyday language.

Yes, absolutely. That is also natural Norwegian.

The difference is mainly in focus:

• Lukten gjør henne kvalm.
  Focuses on the smell as the cause.

• Hun blir kvalm av lukten.
  Focuses more on her reaction: She gets nauseous from the smell.

Both are good Norwegian, and both are useful to know.

Gjør is the present tense of gjøre.

So the sentence can mean either:

• a general fact: The smell makes her nauseous
• something happening now: The smell is making her nauseous

Context tells you which one is meant.

If you wanted the past tense, you would use gjorde:

• Lukten gjorde henne kvalm. = The smell made her nauseous.