Hún krefur hann um svar.

Krefur is the 3rd person singular present form of the verb krefja.

A very useful pattern is:

krefja einhvern um eitthvað
= to demand something from someone

So in your sentence:

• Hún = she
• krefur = demands
• hann = him
• um svar = for an answer / a reply

This is a verb you usually learn together with its case pattern, because that pattern is important in Icelandic.

Because krefja takes a direct object in the accusative case.

So:

• hann = accusative form of hann/he
• honum = dative form, which would be wrong here

In other words, the verb krefja specifically wants:

• a person in the accusative
• plus um
  • the thing being demanded

So Hún krefur hann um svar is correct, but Hún krefur honum um svar is not.

With krefja, the thing demanded is often introduced by um.

So the pattern is:

krefja + accusative person + um + accusative thing

Examples:

• krefja einhvern um skýringu = demand an explanation from someone
• krefja einhvern um peninga = demand money from someone
• krefja einhvern um svar = demand an answer from someone

This is just part of how the verb is constructed. English learners often want to translate word-for-word, but in Icelandic it is best to learn the whole verb pattern.

Svar is in the accusative singular, because it comes after um, and um takes the accusative in this meaning.

It may not look different because svar is a neuter noun, and for many neuter nouns the nominative and accusative singular are the same.

So:

• nominative: svar
• accusative: svar

That is why there is no visible change here.

Because svar is indefinite: an answer / answer.

If you say svarið, that means the answer.

So the difference is:

• um svar = for an answer
• um svarið = for the answer

Both can be grammatically possible, but they mean slightly different things depending on context.

Yes. It follows the basic Icelandic sentence order:

subject + verb + object + prepositional phrase

So:

• Hún = subject
• krefur = verb
• hann = object
• um svar = prepositional phrase

This is a very normal, neutral order.

Icelandic word order can change for emphasis, especially in longer sentences, but this version is the straightforward one.

Yes, and that is a very useful thing to know.

There are two related patterns:

1. krefja einhvern um eitthvað
   = demand something from someone

2. krefjast einhvers
   = demand something

For example:

• Hún krefur hann um svar.
• Hún krefst svars.

These are related, but they are not built the same way.

Notice especially:

• krefur comes from krefja
• krefst comes from krefjast
• krefjast usually takes a genitive object, so svars is genitive

This is a common source of confusion for learners.

Hún is the nominative singular form of the pronoun meaning she.

It is used because it is the subject of the sentence — the person doing the demanding.

Compare:

• hún = she
• hana = her (accusative)
• henni = her (dative)
• hennar = her (genitive)

In this sentence, hún is correct because she is the subject.

A rough guide:

• Hún ≈ hoon
• krefur ≈ KREH-vur
• hann ≈ hatn or hahn depending on speech style
• um ≈ um
• svar ≈ svar with an sv cluster

A rough English-style approximation of the whole sentence is:

hoon KREH-vur hatn um svar

A few pronunciation notes:

• ú is a long vowel, roughly like oo
• r is trilled or tapped
• hv/hn/hl clusters in Icelandic can sound unusual to English speakers, though here hún is simple
• sv in svar may take a little practice

It sounds fairly strong because krefja means to demand, not just to ask.

So this is stronger than verbs like:

• biðja um = ask for
• spyrja = ask

If you use krefja, it suggests insistence, pressure, or a sense that the speaker believes they have a right to the answer.

So learners should understand that this is not a soft, casual request.

A good way is to memorize it as a fixed pattern:

krefja + person in accusative + um + thing in accusative

For example:

• Hún krefur hann um svar.
• Þeir krefja mig um peninga.
• Við krefjumst breytinga. ← related verb, different structure

If you learn krefja by itself, you may forget the cases. If you learn the whole frame, you are much more likely to use it correctly.