Prentarinn er lagaður núna.

Because Icelandic usually adds the definite article to the end of the noun instead of using a separate word like the.

• prentari = printer
• prentarinn = the printer

So -inn here is the masculine singular definite ending.

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

The sentence is about the printer being in a certain condition, so nominative is used.

A useful comparison:

• Prentarinn er lagaður. = The printer is fixed.
  
  • subject, so nominative
• Ég laga prentarann. = I fix the printer.
  
  • object, so accusative

Notice how the form changes from prentarinn to prentarann.

Er is the present tense of að vera, which means to be.

So here:

• er = is

That makes the basic structure:

• Prentarinn = the printer
• er = is
• lagaður = fixed/repaired
• núna = now

Because lagaður has to agree with prentarinn in gender, number, and case.

Prentarinn is:

• masculine
• singular
• nominative

So the matching form is lagaður.

Compare:

• prentarinn = masculine singular → lagaður
• tölvan = feminine singular → löguð
• tækið = neuter singular → lagað

Examples:

• Tölvan er löguð núna. = The computer is fixed now.
• Tækið er lagað núna. = The device is fixed now.

It is originally a past participle of the verb að laga = to fix / repair, but in this sentence it functions very much like an adjective after er.

So er lagaður means something like:

• is repaired
• is fixed
• has been repaired and is now in a fixed state

This is very common in Icelandic.

Mostly a state.

Prentarinn er lagaður núna focuses on the printer’s current condition: it is fixed now.

It does not tell you:

• who repaired it
• exactly when it was repaired
• how it was repaired

So the main idea is the result: the printer is now in working order / repaired.

Yes, the word order can change.

Putting núna at the end is very natural and neutral:

• Prentarinn er lagaður núna.

You can also say:

• Prentarinn er núna lagaður.
• Núna er prentarinn lagaður.

These all mean roughly the same thing, but the emphasis shifts a little.

A useful point: if núna comes first, the verb still stays in second position:

• Núna er prentarinn lagaður.

That is normal Icelandic word order.

Both mean now.

In many situations they are interchangeable, but núna often sounds a little more conversational or emphatic.

So both of these are possible:

• Prentarinn er lagaður núna.
• Prentarinn er lagaður nú.

A learner can safely understand both as now.

The form of lagaður changes to match the subject.

Examples:

• Prentarinn er lagaður núna.
  masculine singular

• Tölvan er löguð núna.
  feminine singular

• Tækið er lagað núna.
  neuter singular

• Prentararnir eru lagaðir núna.
  masculine plural

So this sentence is a good example of Icelandic agreement.

A rough learner-friendly guide is:

• Prentarinn ≈ PREN-ta-rinn
• er ≈ er
• lagaður ≈ LA-ga-thur
• núna ≈ NOO-na

A few helpful pronunciation notes:

• Icelandic stress usually falls on the first syllable of each word.
• The r is typically tapped or rolled.
• The ð in lagaður is soft, somewhat like the th in this, though pronunciation can vary.
• nú has a long oo sound.

So the whole sentence is roughly:

PREN-ta-rinn er LA-ga-thur NOO-na