Ketillinn sýður hratt, svo ég hræri teið með lítilli skeið.

Because Icelandic usually puts the definite article on the end of the noun.

• ketill = kettle
• ketillinn = the kettle
• te = tea
• teið = the tea

The exact article ending changes depending on the noun’s gender, number, and case. So unlike English, Icelandic often says the-noun as a single word.

Icelandic has no indefinite article. So a bare noun can mean a or an depending on context.

• skeið = spoon / a spoon
• lítilli skeið = a small spoon

If you really want to emphasize one, Icelandic can use einn / ein / eitt, but normally it is not needed.

This sentence shows three very common cases:

• ketillinn — nominative, because it is the subject of sýður
• teið — accusative, because it is the direct object of hræri
• lítilli skeið — dative, because með takes the dative here

So the sentence is a nice example of how Icelandic marks grammatical roles with case, not just word order.

In Icelandic, the simple present often covers both:

• boils
• is boiling

So ketillinn sýður can mean the kettle boils or the kettle is boiling, depending on context.

English uses a separate progressive form very often, but Icelandic does not need one here. If you want to strongly emphasize an ongoing action, Icelandic can use vera að + infinitive, but the plain present is very common.

Because hratt is an adverb, and hraður is an adjective.

• hraður = fast, rapid
• hratt = quickly, fast

Here the word describes how the kettle is boiling, so you need an adverb:

• Ketillinn sýður hratt = The kettle is boiling quickly

A useful pattern is that Icelandic adverbs are often the same as the neuter singular form of the adjective.

Here svo means so or therefore. It is linking the first clause to the result in the second clause.

In this kind of sentence, svo works like a conjunction, so it is normal to get:

• svo ég hræri teið... = so I stir the tea...

If svo were being used more like then as a sentence adverb, you could get inversion in other contexts. But in this sentence, svo ég hræri... is a normal pattern.

Because hræri is the 1st person singular present form of hræra, meaning to stir.

So:

• að hræra = to stir
• ég hræri = I stir / I am stirring

This is just the present-tense form that agrees with ég.

Because með takes the dative here, and lítill has to match skeið in case, number, and gender.

• skeið is feminine singular
• after með, it is in the dative
• so lítill becomes lítilli

That gives:

• með lítilli skeið = with a small spoon

So the ending on lítilli is there because of grammar, not because it is a different word.

This is very common in Icelandic. Sometimes the noun’s case form is not visibly different, but the adjective still shows the case clearly.

So in lítilli skeið:

• the adjective clearly shows dative feminine singular with -i
• the noun skeið happens to look the same here as in some other forms

That does not mean the noun has no case. It just means its dative form is not visibly different in this example. The adjective helps reveal the grammar.