Ég set stólinn nær glugganum.

Setja is the infinitive: to put / to place / to set.

In the sentence, set is the 1st person singular present tense form, so it matches ég:

• ég set = I put / I am putting
• þú setur = you put
• hann / hún / það setur = he / she / it puts

So Ég set... literally means I put... or, depending on context, I am putting....

Because stólinn is the direct object of the verb set.

The basic noun is:

• stóll = chair (nominative singular, indefinite)

But after a verb like setja, the thing being placed is normally in the accusative.
The accusative singular of stóll is stól.

Then the definite article -inn is added:

• stól = a chair (accusative singular)
• stólinn = the chair (accusative singular definite)

So:

• Ég set stólinn... = I put the chair...

Because nær takes the dative in this sentence.

The basic noun is:

• gluggi = window

Here it appears as:

• glugganum = the window in the dative singular definite

So the structure is:

• nær glugganum = nearer to the window / closer to the window

This is a very common thing in Icelandic: a word like nær controls a certain case, and the noun after it changes form accordingly.

Here nær means nearer or closer.

So the sentence is not just saying that the chair is by the window. It suggests movement to a position closer than before.

Compare the idea:

• nálægt glugganum = near the window
• nær glugganum = nearer / closer to the window

So Ég set stólinn nær glugganum is essentially:

• I put the chair closer to the window
• or more literally, I put the chair nearer the window

Because Icelandic often expresses that idea through case, not through a separate word.

In English, we say:

• closer to the window

In Icelandic, nær is followed directly by a noun in the dative:

• nær glugganum

So the meaning of English to is built into the Icelandic construction. You do not need a separate word there.

It can mean either, depending on context.

The Icelandic simple present often covers both:

• I put
• I am putting

So Ég set stólinn nær glugganum can mean:

• I put the chair closer to the window
• I am putting the chair closer to the window

If you want to be especially explicit about an action happening right now, Icelandic can also use a progressive-type construction such as ég er að setja..., but the simple present is very normal.

This is the most straightforward neutral order:

• Ég = subject
• set = verb
• stólinn = direct object
• nær glugganum = adverbial/prepositional phrase

So it follows a very familiar pattern:

• Subject + Verb + Object + Other information

That said, Icelandic word order is more flexible than English, and different word orders can be used for emphasis. But this version is the natural neutral statement.

Because the two nouns have different jobs in the sentence.

• stólinn is the thing being moved/placed → so it is in the accusative
• glugganum is the noun after nær → so it is in the dative

So even though both mean the + noun, they do not look the same, because Icelandic marks grammatical function with case.

That is one of the most important things to notice in Icelandic sentences: noun endings change depending on their role in the sentence.