Hun lærer japansk.

Because lærer can be either:

• a verb: learns / is learning
• a noun: teacher

In Hun lærer japansk, it is a verb, because it comes after the subject hun and works as the action of the sentence.

So the structure is:

• Hun = she
• lærer = learns / is learning
• japansk = Japanese

If lærer were a noun, you would need a different sentence structure, for example:

• Hun er lærer = She is a teacher

So context and sentence structure tell you which meaning is intended.

It can mean both.

In Norwegian, the present tense often covers both:

• She learns Japanese
• She is learning Japanese

So lærer is the present tense of å lære and can describe:

• a general fact or habit
• something happening now

Norwegian usually does not need a special progressive form like English is learning.

Because japansk here is being used as the name of a language, and language names are normally used without an article in Norwegian.

So you say:

• Hun lærer japansk = She is learning Japanese
• Jeg snakker engelsk = I speak English
• Vi studerer norsk = We study Norwegian

This is similar to English, where you also normally say She learns Japanese, not She learns the Japanese.

In Norwegian, names of languages are usually written with a lowercase letter unless they begin the sentence.

So:

• japansk
• norsk
• engelsk
• tysk

This is different from English, where language names are capitalized:

• Japanese
• Norwegian
• English
• German

So Hun lærer japansk is written correctly in Norwegian.

Lærer is the present tense of the verb å lære.

A basic pattern is:

• å lære = to learn
• lærer = learn / learns / am learning / is learning / are learning, depending on context

Examples:

• Jeg lærer = I learn / I am learning
• Hun lærer = She learns / She is learning
• De lærer = They learn / They are learning

Norwegian verbs do not change by person the way English verbs do. So the same present-tense form is used with all subjects.

This sentence uses the normal basic word order:

• Hun = subject
• lærer = verb
• japansk = object

So it follows the common pattern:

Subject + Verb + Object

That gives:

Hun lærer japansk.

This is the most straightforward kind of Norwegian sentence.

No. With a language, å lære usually takes the object directly.

So you say:

• Hun lærer japansk
• Jeg lærer norsk
• Vi lærer spansk

There is no extra preposition between lærer and the language.

Yes. In Norwegian, words like japansk, norsk, and engelsk can function as language names, even though they also look like adjectives.

So:

• japansk mat = Japanese food
  Here japansk is an adjective.

But:

• Hun lærer japansk = She is learning Japanese
  Here japansk refers to the language.

This is very common in Norwegian.

A useful learner-friendly approximation is:

• lærer ≈ LAIR-er

The tricky part is æ, which sounds somewhat like the vowel in English air, though not exactly the same in every accent.

So the word has two parts:

• læ-
• -rer

If you already know å lære, then lærer is just the present-tense form of that verb.

Normally, no.

Hun lærer japansk means She learns / is learning Japanese, not She teaches Japanese.

To say She teaches Japanese, Norwegian would usually use something like:

• Hun underviser i japansk = She teaches Japanese
• Hun er japansklærer = She is a Japanese teacher

So in your sentence, lærer is understood as learns, not teaches.

The infinitive is å lære, which means to learn.

So the forms are:

• å lære = to learn
• lærer = learns / is learning

Example:

• Hun vil lære japansk = She wants to learn Japanese
• Hun lærer japansk = She learns / is learning Japanese

This is a very useful verb in beginner Norwegian.