Hun stoler på vitenskapen.

Because the full Norwegian expression is å stole på, which means to trust or to rely on someone or something.

So in this sentence:

• stoler = present tense of å stole
• på = a required preposition in this expression

You should learn å stole på as a unit, much like an English phrasal verb.

Examples:

• Jeg stoler på deg. = I trust you.
• Vi stoler på legen. = We trust the doctor.

It is simply the preposition that goes with å stole when it means to trust.

In English, we say trust someone/something with no preposition, but Norwegian uses stole på. This is an idiomatic difference, so it is best to memorize it as a fixed pattern.

Not every Norwegian preposition matches English directly.

Stoler is the present tense form of å stole.

Infinitive:

• å stole på = to trust

Present tense:

• jeg stoler
• du stoler
• hun stoler
• vi stoler

A useful point for English speakers: Norwegian verbs do not change according to the subject the way English does. So you do not get different present forms like I trust vs she trusts. It stays stoler for all persons.

Because Norwegian verbs do not add an extra ending just because the subject is he/she/it.

Compare English:

• I trust
• she trusts

Norwegian:

• jeg stoler
• hun stoler

So hun does not force a special verb ending.

Hun means she.

It is the subject pronoun used for a female person or an animal/person referred to as female.

Examples:

• Hun leser. = She reads.
• Hun kommer snart. = She is coming soon.

Vitenskapen is the definite singular form of vitenskap.

• vitenskap = science
• vitenskapen = the science / science as a known concept

The ending -en is a common definite ending for masculine nouns, and vitenskap is usually treated as masculine in Bokmål.

In this sentence, vitenskapen often sounds natural when referring to science as an established body of knowledge or institution.

Formally, yes: vitenskapen is the definite form, so it literally corresponds to the science.

But in actual use, Norwegian often uses the definite form where English would simply say science in a general sense.

So Hun stoler på vitenskapen is a natural way to express She trusts science.

This kind of mismatch between English and Norwegian is common.

Yes, but it means something a little different.

• Hun stoler på vitenskapen = She trusts science.
• Hun tror på vitenskapen = She believes in science.

The difference is similar to English:

• trust suggests confidence in its reliability
• believe in can suggest faith in its value, truth, or effectiveness

In many contexts they may overlap, but stoler på is the more direct match for trusts.

This is normal Norwegian word order for a main statement:

• Hun = subject
• stoler = finite verb
• på vitenskapen = prepositional phrase

So the pattern is:

Subject + verb + rest

If you turned it into a yes/no question, the word order would change:

• Stoler hun på vitenskapen? = Does she trust science?

That verb-second pattern is very important in Norwegian.

Yes.

For example:

• Hun stoler på den. = She trusts it.

Here, den refers back to a masculine noun like vitenskapen.

This is useful because it shows that på stays with the verb expression:

• stole på noe = trust something
• stole på den = trust it

In this sentence, it is singular and refers to science as a whole.

You can have a plural form in other contexts:

• vitenskaper = sciences

For example:

• naturvitenskaper = natural sciences

But when talking generally about science as a broad concept, singular is much more likely:

• vitenskap
• vitenskapen

A simple approximate pronunciation is:

Hoon STOH-ler poh VEE-ten-skah-pen

A few notes:

• Hun sounds roughly like hoon, but with a Norwegian u
• stoler has stress on the first syllable: STO-
• på has a long vowel, roughly like paw/po
• vitenskapen is stressed on VI

If you want very natural pronunciation, it helps to learn the whole sentence as one rhythm: Hun stoler på vitenskapen.