Hun forklarer teorien.

Hun is a subject pronoun. It is the Norwegian word used for she.

In this sentence, hun is the subject — the person doing the action.

In Norwegian, verbs do not change according to the subject the way they do in English.

So you get:

• jeg forklarer = I explain / I am explaining
• du forklarer = you explain / are explaining
• hun forklarer = she explains / is explaining
• vi forklarer = we explain / are explaining

The verb form stays the same.

Forklarer is the present tense of forklare.

The infinitive is:

• å forklare = to explain

The present tense is formed here as:

• forklare → forklarer

Yes. Very often, Norwegian present tense can cover both the simple present and the present progressive in English.

So hun forklarer teorien can mean:

• she explains the theory
• she is explaining the theory

The exact meaning depends on context.

Because Norwegian usually expresses the by adding a definite ending to the noun.

Here:

• teori = theory
• teorien = the theory

So instead of a separate word before the noun, Norwegian often puts the definiteness on the end of the noun itself.

The basic dictionary form is teori.

You can think of the forms like this:

• en teori = a theory
• teorien = the theory

So -en here is the definite singular ending.

Sometimes, yes — but not in a simple sentence like this.

With a plain noun, Norwegian usually says:

• teorien = the theory

But when there is an adjective, Norwegian often uses both a separate definite word and the noun ending:

• den nye teorien = the new theory

So in your sentence, teorien by itself is exactly what you want.

The basic order is:

• subject + verb + object

So here:

• Hun = subject
• forklarer = verb
• teorien = object

This is the normal order in a simple statement.

Yes, but Norwegian still follows an important rule in main clauses: the finite verb is usually in second position.

For example:

• Hun forklarer teorien.
• I dag forklarer hun teorien. = Today she explains / is explaining the theory.

Notice that when I dag comes first, the verb forklarer still stays in second position, and hun moves after it.

You usually put ikke after the verb:

• Hun forklarer ikke teorien.

That means she does not explain / is not explaining the theory.

In a yes/no question, Norwegian usually puts the verb before the subject:

• Forklarer hun teorien?

That means Does she explain the theory? or Is she explaining the theory?

A careful approximate pronunciation is:

• Hun → roughly like hoon, but with a Norwegian u sound, not a normal English oo
• forklarer → for-KLAR-er
• teorien → teh-oo-REE-en or teh-oh-REE-en, depending on accent and speaking style

A few useful notes:

• r is pronounced much more clearly than in most kinds of English
• teorien has multiple syllables: te-o-ri-en
• pronunciation varies by dialect, sometimes quite a lot

This is Bokmål.

A Nynorsk version would normally use:

• Ho forklarer teorien.

So hun is a clear sign that your sentence is Bokmål.