Frátektin er tilbúin.

It breaks down like this:

• frátektin = the noun frátekt with the definite article attached
• er = the present-tense form of vera (to be)
• tilbúin = an adjective meaning ready/prepared, in the form that matches the noun

So the sentence structure is:

• subject
  • verb
    • predicate adjective

In Icelandic, the is very often attached to the end of the noun instead of being a separate word.

So:

• frátekt = an indefinite noun
• frátektin = the
  • noun

This attached ending is the definite article.

That is one of the first big differences from English: Icelandic usually says noun + the-ending, not a separate the before the noun.

In this sentence, frátekt is feminine.

You can tell from the grammar around it:

• the definite form frátektin fits a feminine noun here
• the adjective is tilbúin, which is the feminine singular form

When learning the word, it is a good idea to remember it as:

• frátekt (f.)

In Icelandic, noun gender matters because adjectives and some other words must match it.

Because Icelandic adjectives must agree with the noun they describe.

They usually match in:

• gender
• number
• case

Here, the noun is feminine singular, so the adjective must also be feminine singular:

• tilbúinn = masculine singular
• tilbúin = feminine singular
• tilbúið = neuter singular

So tilbúin is the correct form because it matches frátektin.

Because here tilbúin is a predicate adjective: it comes after the verb to be and describes the subject.

English does the same thing:

• The ... is ready

not

• The ready ... in this kind of sentence

So Icelandic uses:

• Frátektin er tilbúin

This is different from an adjective placed directly before a noun, where it is part of the noun phrase itself.

A useful comparison:

• bíllinn er stór = the car is big
• stóri bíllinn = the big car

So in your sentence, tilbúin is in the normal place for a predicate adjective.

Er is a present-tense form of the verb vera (to be).

In this sentence, it means is.

A few useful forms are:

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

So here er is the correct singular form with a third-person singular subject.

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

In a basic sentence like:

• X er Y

the X part is normally nominative.

The adjective tilbúin also appears in the matching nominative form, because predicate adjectives with vera agree with the subject.

So here you have:

• frátektin = nominative feminine singular
• tilbúin = nominative feminine singular

You would usually look up:

• frátekt for the noun
• vera for the verb
• tilbúinn for the adjective

That is because Icelandic dictionaries normally list:

• nouns in their basic indefinite form
• verbs in the infinitive
• adjectives in the masculine singular nominative form

So even though the sentence has frátektin and tilbúin, the dictionary forms are frátekt and tilbúinn.

A few helpful pronunciation points:

• Icelandic words are usually stressed on the first syllable
• so the main stress is on FRÁ- in frátektin and on TIL- in tilbúin

A rough guide for an English speaker would be:

• FRAU-tek-tin er TIL-boo-in

Very roughly:

• á sounds somewhat like the vowel in now
• ú sounds roughly like oo in food

Also, the accent marks in Icelandic do not mainly show stress; they mostly show vowel quality.

Because adjectives after vera normally use the predicate form, not the attributive definite form.

In other words, Icelandic treats:

• the car is big

differently from

• the big car

Compare:

• bíllinn er stór = the car is big
• stóri bíllinn = the big car

Your sentence works like the first pattern:

• Frátektin er tilbúin

So even though the noun is definite, the adjective is in the normal predicate form tilbúin, not an attributive weak form.