Hringurinn hennar er á náttborðinu.

Because hringurinn means the ring, while hringur means just a ring / ring.

• Dictionary form: hringur
• Definite singular nominative: hringurinn

Icelandic usually puts the definite article on the end of the noun instead of using a separate word like English the.

So:

• hringur = ring
• hringurinn = the ring

Yes, literally it looks like the ring her, but that is a normal Icelandic way to express possession.

In Icelandic, possession is often shown with:

• a definite noun
• followed by a possessive word

So:

• hringurinn hennar = her ring
• bíllinn minn = my car
• húsið þeirra = their house

To an English speaker it can feel redundant because English usually uses either the or a possessive, not both. But in Icelandic this structure is very common and natural.

Hennar is the genitive form of hún (she).

Here it works as a possessive word meaning her.

So:

• hún = she
• hana = her (object)
• henni = to her
• hennar = her / hers

In this sentence, hennar tells you who the ring belongs to.

In this sentence, the natural English translation is her.

Grammatically, hennar is a genitive form that can correspond to English her or hers, depending on context. But in hringurinn hennar, it is simply a possessive: her ring.

So the safest way to understand it here is:

• hringurinn hennar = her ring

Hringurinn is in the nominative singular.

That is because it is the subject of the sentence:

• Hringurinn hennar = the thing being talked about
• er = is
• á náttborðinu = on the bedside table

In Icelandic, subjects are usually in the nominative case, just like in many other Indo-European languages.

Because after á, Icelandic uses different cases depending on meaning:

• dative for location: being on something
• accusative for motion toward something: going onto something

Here the ring is already located on the bedside table, so this is location, not movement. That is why Icelandic uses the dative:

• á náttborðinu = on the bedside table

Compare:

• Hringurinn er á náttborðinu. = The ring is on the bedside table.
• Hún setti hringinn á náttborðið. = She put the ring onto the bedside table.

So:

• náttborðið = accusative/nominative definite form
• náttborðinu = dative definite form

Á is one of those Icelandic prepositions that can take more than one case.

A very useful rule is:

• location / no movement → dative
• movement to a destination → accusative

In this sentence, the ring is simply on the bedside table. Nothing is moving. So á takes the dative:

• á náttborðinu

This same pattern appears with other prepositions too, so it is worth learning early.

You have to be careful, because moving hennar can change the meaning.

• Hringurinn hennar er á náttborðinu. = Her ring is on the bedside table.
• Hringurinn er á náttborðinu hennar. = The ring is on her bedside table.

In the first sentence, hennar belongs with hringurinn.
In the second, hennar belongs with náttborðinu.

So word placement matters a lot for showing what belongs to her.

Normally, no—not in an ordinary neutral sentence like this.

The most natural everyday Icelandic expression is:

• hringurinn hennar

Putting the possessive first, as in hennar hringur, sounds marked, unusual, or context-dependent. A learner should treat hringurinn hennar as the standard pattern here.

Because sinn/sín/sitt is a reflexive possessive. It usually refers back to the subject of the clause.

In this sentence, the subject is hringurinn hennar (her ring), not she. So sinn would not fit the meaning.

Compare:

• Hringurinn hennar er á náttborðinu. = Her ring is on the bedside table.
• Hún setti hringinn sinn á náttborðið. = She put her own ring onto the bedside table.

In the second sentence, hún is the subject, so sinn can refer back to her own ring.

The two nouns are:

• hringur = ring — masculine
• náttborð = bedside table / nightstand — neuter

That helps explain the endings:

• hringur → hringurinn
• náttborð → náttborðinu

Learning the gender of each noun is important in Icelandic, because gender affects articles, adjectives, and case endings.