Bækur úr safnkostinum eru í lestrarsal almenningsbókasafnsins.

Bækur is the nominative plural of bók (book).

In this sentence, Bækur is the subject, so it appears in the nominative case. Icelandic uses the plural here because the sentence is talking about books rather than a single book.

A quick pattern:

• bók = a book
• bækur = books

The vowel change from ó to æ is part of the noun’s normal plural pattern.

Because the subject is plural.

• er = is (singular)
• eru = are (plural)

Since Bækur means books, the verb has to agree with it:

• Bókin er ... = The book is ...
• Bækur eru ... = The books are ...

So eru is simply the correct plural form of vera (to be).

Úr usually means out of / from. It governs the dative case, so the noun after it must be in the dative.

That is why you get:

• dictionary form: safnkostur
• after úr: safnkostinum

So the structure is:

• úr + dative

Examples:

• úr húsinu = out of the house
• úr skólanum = from the school
• úr safnkostinum = from the collection / holdings

Safnkostinum is the dative singular definite form of safnkostur.

It breaks down like this:

• safnkostur = collection, holdings
• safnkosturinn = the collection / the holdings
• safnkostinum = to/from/in the collection, depending on the preposition

In this sentence, it appears after úr, which requires dative.

Also, the ending -num includes the definite article. Icelandic usually adds the to the end of the noun instead of using a separate word.

So safnkostinum means roughly the collection or the holdings, in the dative case.

Because Icelandic normally uses a suffixed definite article.

Instead of a separate word like English the, Icelandic often attaches it to the noun:

• bókasafn = library
• bókasafnið = the library

In your sentence, you can see this in forms like:

• safnkostinum = the collection (with case ending)
• almenningsbókasafnsins = of the public library

So English uses a separate word, but Icelandic often builds definiteness into the noun ending.

Because í can take either the accusative or the dative, depending on meaning:

• accusative = motion into
• dative = location in

Here the books are already located there, so it is location, not movement. That means í takes the dative.

So:

• í lestrarsal = in the reading room

Compare:

• Ég fer í skólann. = I go into the school.
  
  • movement, so accusative
• Ég er í skólanum. = I am in the school.
  
  • location, so dative

The same principle is being used here.

Yes. It is a compound noun:

• lestur = reading
• salur = hall, room

Together:

• lestrarsalur = reading room

Compounds are extremely common in Icelandic, much as in German. English often writes similar ideas as two words, but Icelandic frequently makes them into one word.

So í lestrarsal literally means in [a] reading-room.

It is long because it is both a compound noun and a genitive definite form.

Break it down:

• almenningur = the public, general public
• bókasafn = library
• almenningsbókasafn = public library
• almenningsbókasafnsins = of the public library

The ending -sins shows that the noun is:

• genitive singular
• definite

So lestrarsal almenningsbókasafnsins means:

• the reading room of the public library
• or more naturally in English, the public library’s reading room

Because Icelandic often uses the genitive case to show possession or close relationship.

Here, the reading room belongs to or is associated with the public library:

• lestrarsal almenningsbókasafnsins

Literally:

• reading room of-the-public-library

This is a very common Icelandic structure. English can express the same idea with either:

• the reading room of the public library
• the public library’s reading room

Because lestrarsal is indefinite here.

Icelandic does not need to mark every noun as definite in the same way English does. In this sentence, the definiteness is carried mainly by almenningsbókasafnsins (of the public library), and the phrase works naturally without making lestrarsal itself definite.

So Icelandic says:

• í lestrarsal almenningsbókasafnsins

where English would usually say:

• in the reading room of the public library

In other words, Icelandic and English do not always match article usage one-for-one.

Yes, it is quite normal.

The sentence is structured like this:

• Bækur = subject
• úr safnkostinum = modifier describing which books
• eru = verb
• í lestrarsal almenningsbókasafnsins = location

So the overall pattern is:

• [Subject] [description of subject] [verb] [location]

That is a natural way to build a sentence in Icelandic.

You could think of úr safnkostinum as narrowing down which books are being talked about:

• Books from the collection are in the reading room ...

Yes, and that is the most natural reading.

In this sentence, úr safnkostinum tells you which books:

• Bækur úr safnkostinum = books from the collection

So the phrase belongs semantically with the noun phrase, even though it comes before the verb.

This is very natural in Icelandic and English alike:

• Books from the collection
• Students from Iceland
• Letters from the archive

Yes:

• Bækur

  • noun
  • from bók
  • nominative plural
  • subject
  • books

• úr

  • preposition
  • means from / out of
  • takes the dative

• safnkostinum

  • noun
  • from safnkostur
  • dative singular definite
  • the collection / the holdings

• eru

  • verb
  • present tense of vera
  • are

• í

  • preposition
  • means in
  • here it takes the dative because this is location

• lestrarsal

  • noun
  • from lestrarsalur
  • dative singular
  • reading room

• almenningsbókasafnsins

  • noun
  • from almenningsbókasafn
  • genitive singular definite
  • of the public library

So the grammar is very compact, but each ending has a clear job.

Not exactly.

• safn often means collection, and in many contexts also museum
• safnkostur is more specifically the holdings or materials in a collection

In a library context, safnkostur can refer to the books and other items that belong to the library’s collection.

So úr safnkostinum suggests from the library’s holdings/collection, which is slightly more specific than just úr safninu.

Probably these three:

1. Prepositions control case

   • úr
     • dative
   • í
     • dative here because it expresses location

2. The definite article is usually attached to the noun

   • safnkostinum
   • almenningsbókasafnsins

3. Icelandic loves compounds

   • lestrarsalur
   • almenningsbókasafn

If you can spot those three things, the sentence becomes much easier to understand grammatically.