Learn Hardcore Icelandic: Hún segir nafnið sitt þegar hún kynnir sig. - She says her name when she introduces herself.

In Icelandic, when talking about things that are clearly unique to the person (like their name, body parts, family members, etc.), the definite form is very common, where English would just use a possessive:

Hún segir nafnið sitt. ≈ “She says her name.”
Literally: “She says the name her-own.”

Nafn sitt would sound more like “a name of hers” or be used in a more abstract or less typical context; for this everyday sentence, nafnið sitt is the idiomatic choice.

What’s the difference between sitt and hennar for “her”?

Sitt is reflexive; hennar is not.

sinn / sín / sitt = reflexive possessive (“his/her own”), always refers back to the subject of the same clause.
hennar = “her” (belonging to some female person, not necessarily the subject).

In this sentence, sitt refers back to hún in the same clause, so it means her own name:

Hún segir nafnið sitt. = She says her own name (her own name, not someone else’s).

If you said:

Hún segir nafnið hennar.

then hennar would refer to some other woman (or just some other female person already mentioned), not to hún herself. That would mean something like “She says her (another woman’s) name.”

Why does it say kynnir sig instead of just kynnir?

Because að kynna sig is the standard way to say “to introduce oneself”.

kynna = to introduce (someone or something).
sig = reflexive object pronoun (“oneself”).

So:

Hún kynnir sig. = She introduces herself.
Literally: “She introduces herself (her-self).”

Without sig, hún kynnir would be incomplete; you’d be left with “she introduces …” but no object. If you used a non‑reflexive pronoun instead:

Hún kynnir hana. = She introduces her (some other woman).

So sig is needed to show it’s the same person as the subject.

Why is it sig in one place and sitt in another? Aren’t they both “herself/her own”?

They are both reflexive, but they are different types of words:

sig = reflexive pronoun (object): “himself / herself / themselves”.
sinn / sín / sitt = reflexive possessive adjective: “his/her/their own” (modifies a noun).

In the sentence:

nafnið sitt: sitt describes the noun nafnið (whose name?), so it’s a possessive.
kynnir sig: sig is standing alone as the direct object of the verb kynnir (whom does she introduce?), so it’s an object pronoun.

So:

sitt = “her own” (possessive, modifies a noun)
sig = “herself” (object pronoun)

How is segir formed from segja, and how is kynnir formed from kynna?

Both are 3rd person singular present tense forms.

From segja (to say):

ég segi – I say
þú segir – you say (singular)
hann/hún/það segir – he/she/it says
við segjum – we say
þið segið – you say (plural)
þeir/þær/þau segja – they say

So hún segir = “she says”.

From kynna (to introduce):

ég kynni – I introduce
þú kynnir – you introduce
hann/hún/það kynnir – he/she/it introduces
við kynnum – we introduce
þið kynnið – you (pl.) introduce
þeir/þær/þau kynna – they introduce

So hún kynnir sig = “she introduces herself”.

What case is nafnið in here, and why?

Nafnið is in the accusative singular because it is the direct object of segir.

Verb: segir – “(she) says”
Direct object: nafnið sitt – “her own name” (what does she say?)

For neuter nouns like nafn, the nominative and accusative singular look the same in form:

Nominative: nafn / nafnið
Accusative: nafn / nafnið

So you can’t see the case from the ending alone, but the function (direct object) tells you it’s accusative.

Does þegar change the word order? Could it be … þegar kynnir hún sig?

In a subordinate clause introduced by þegar, Icelandic normally uses subject–verb order (SVO), not verb‑second (V2) order.

So:

… þegar hún kynnir sig. = correct, neutral statement.
… þegar kynnir hún sig. = ungrammatical in normal prose/speech.

Compare:

Main clause: Hún kynnir sig. (subject–verb–object) or Síðan kynnir hún sig. (adverb–verb–subject–object; V2)
Subordinate clause after þegar: þegar hún kynnir sig (subject before verb).

So þegar opens a subordinate clause and removes the usual V2 word order that main clauses have.

Why is hún repeated? Could I leave out the second hún and say … þegar kynnir sig?

You cannot normally drop the subject pronoun in Icelandic; it’s not a “pro‑drop” language like Spanish or Italian.

So you need to repeat hún in the second clause:

Hún segir nafnið sitt þegar hún kynnir sig. = correct.
Hún segir nafnið sitt þegar kynnir sig. = incorrect / ungrammatical.

The second hún is the explicit subject of the subordinate clause hún kynnir sig.

What’s the difference in meaning between segir nafnið sitt and kynnir sig? Don’t they both have to do with introductions?

They are doing related but different things:

segja nafnið sitt = “to say one’s name”.
You’re just stating your name out loud.
kynna sig = “to introduce oneself”.
This is the act of introducing yourself, which can involve more than just your name (e.g. job, where you’re from, etc.).

In this sentence, the idea is:

When she introduces herself (þegar hún kynnir sig),
she says her name (hún segir nafnið sitt).

You would not normally say *hún kynnir nafnið sitt for “she says her name”; kynna is used for introducing people or presenting something, not simply saying a name.

Could I say segir sitt nafn instead of segir nafnið sitt?

Yes, Hún segir sitt nafn is grammatically correct and understandable, but Hún segir nafnið sitt is more idiomatic in everyday speech.

Rough nuance:

segir nafnið sitt – very natural, like “she says her name” (with the idea that each person has their one specific name).
segir sitt nafn – more literally “she says her own name”; fine, but slightly less common phrasing here.

Both are acceptable; learners will sound very natural using segir nafnið sitt in this context.

How is this sentence pronounced, especially segir, nafnið, and kynnir?

Approximate pronunciation (using English‑friendly hints):

Hún ≈ “hoon” (long ú; lips rounded)
segir ≈ “SAY‑yir”
- The g is soft, almost like a y sound: [ˈsei.jɪr]
nafnið ≈ “NAHV‑nith”
- Written fn is usually pronounced [pn] or [vn]; here it sounds like [navnɪð] or [napnɪð], depending on the speaker.
sitt ≈ “sit” (short vowel, double t pronounced clearly)
þegar ≈ “THEH‑gar” (like English th in “thing”: [ˈθeːɣar])
kynnir ≈ “KIN‑nir”
- y is like short i in “bit”, double nn is clearly pronounced.
sig ≈ “sihg” (short i, final g like a soft [ɣ] or [k]-ish in some accents; often sounds almost like “sihk”).