Ný bók er á borðinu.

Word by word:

• ný = new
• bók = book
• er = is
• á = on
• borðinu = the table

So the sentence means A new book is on the table.

Because ný has to agree with bók.

In Icelandic, adjectives change form depending on the noun’s:

• gender
• number
• case

bók is:

• feminine
• singular
• nominative here

So the adjective must also be feminine singular nominative, which gives ný.

For comparison:

• nýr stóll = a new chair (masculine)
• ný bók = a new book (feminine)
• nýtt borð = a new table (neuter)

bók is in the nominative case because it is the subject of the sentence.

The subject is the thing that is somewhere: the new book.

So in:

• Ný bók = the subject
• er = the verb
• á borðinu = the location

That is why bók appears in its nominative form.

Because borðinu means the table in the dative singular.

There are two things happening here:

1. borð is the noun table
2. -inu is the ending for the definite article plus the dative singular form

So:

• borð = table
• borðið = the table (nominative/accusative)
• borðinu = the table (dative)

In this sentence, the preposition á takes the dative when it expresses location, so we get á borðinu = on the table.

Because á can take different cases depending on meaning.

A very common rule in Icelandic is:

• location / being somewhere → often dative
• movement toward a place → often accusative

Here the book is already located on the table, so it is location, not motion. That is why Icelandic uses:

• á borðinu = on the table

Compare:

• Bókin er á borðinu. = The book is on the table.

  • location → dative

• Ég set bókina á borðið. = I put the book onto the table.

  • motion toward a surface → accusative

Because Icelandic normally does not have an indefinite article like English a/an.

So:

• bók can mean book or a book
• ný bók can mean new book or a new book

Whether English should use a is understood from context.

Icelandic does have a way to mark the, but it is usually attached to the end of the noun instead of being a separate word.

That is how Icelandic usually forms the definite article.

Instead of a separate word like English the, Icelandic often adds the article to the end of the noun.

Examples:

• borð = table
• borðið = the table
• bók = book
• bókin = the book

Because the noun also changes for case, the form of the ending changes too. That is why you see borðinu here rather than just borð or borðið.

Yes. That is a natural Icelandic sentence too.

Both mean essentially the same thing:

• Ný bók er á borðinu
• Á borðinu er ný bók

The difference is mainly emphasis or information structure.

• Ný bók er á borðinu starts with the subject: a new book
• Á borðinu er ný bók starts with the location: on the table

English can do something similar:

• A new book is on the table
• On the table is a new book

The second is a bit more marked in English, but in Icelandic this kind of word order change is quite common.

er is the third person singular present form of the verb vera = to be.

So:

• ég er = I am
• þú ert = you are
• hann / hún / það er = he / she / it is

In this sentence, the subject is singular, so er is the correct form:

• Ný bók er á borðinu = A new book is on the table

If the subject were plural, the verb would change:

• Nýjar bækur eru á borðinu = New books are on the table

Because grammatical gender in Icelandic is a property of the noun itself, not a statement about real-world sex.

Icelandic nouns belong to one of three genders:

• masculine
• feminine
• neuter

So bók is simply a feminine noun, and words connected to it, like adjectives, must match that gender.

This is different from English, where nouns usually do not have grammatical gender.

You would normally say:

• Nýja bókin er á borðinu.

Here both the adjective and noun become definite:

• bókin = the book
• nýja = the adjective form used with a definite feminine singular noun

So compare:

• Ný bók er á borðinu. = A new book is on the table.
• Nýja bókin er á borðinu. = The new book is on the table.