Strætóinn fer suður núna.

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

So:

• strætó = a bus / bus
• strætóinn = the bus

The ending -inn is the definite article here. This is very common in Icelandic.

It is nominative singular definite.

That is the form you expect for the subject of the sentence:

• Strætóinn = the bus
• it is the thing doing the action, so it appears in the nominative case

The noun strætó is masculine, which is why the definite ending here is -inn.

Not necessarily. It is capitalized here because it is the first word of the sentence.

In Icelandic, strætó can mean bus as a common noun. There is also Strætó as the name of the public bus company in Iceland, but in this sentence the capitalization alone does not prove that it is a proper name, because sentence-initial words are capitalized anyway.

Fer is the present tense of fara, which usually means to go, to travel, or sometimes to leave, depending on context.

So fer can mean:

• goes
• is going
• travels
• leaves

With a bus, English might translate it in different ways depending on the situation, even though Icelandic uses the same verb.

Because Icelandic, like English, uses a conjugated verb in a normal sentence.

• fara = to go (infinitive)
• fer = goes / is going (present tense, singular)

Since the subject is singular, strætóinn, the verb is also singular: fer.

Because suður here works as a directional adverb meaning southward / to the south.

Icelandic often uses direction words directly after motion verbs:

• fara suður = go south
• fara norður = go north
• fara út = go out

So no separate word for to is needed here.

In this sentence it is best understood as an adverb of direction.

It tells you where the bus is going. It does not describe the bus itself, and it is not functioning as a noun.

A useful contrast is:

• suður = southward / to the south after motion
• í suðri = in the south for location

So fer suður is about movement, not location.

Both mean now, but núna is very common in everyday speech and often feels a little more natural or emphatic in conversational Icelandic.

Very roughly:

• nú = now
• núna = now / right now

In many contexts they can overlap, but núna often sounds a bit more like right now.

Because that is a very natural word order in Icelandic:

• Strætóinn = subject
• fer = verb
• suður = direction
• núna = time

So the sentence follows a simple pattern like:

The bus goes south now.

But Icelandic word order is somewhat flexible. For example, you could also say:

• Núna fer strætóinn suður.

That is also grammatical. Icelandic often follows a verb-second pattern, so when an adverb like núna comes first, the finite verb fer usually comes next.

It can mean slightly different things depending on context.

With fer, possible English interpretations include:

• The bus is going south now.
• The bus is heading south now.
• The bus leaves southbound now.

If you are talking about a bus route or a departure board, English might prefer is leaving or is heading. If you are simply describing motion, is going south now works well.

So the Icelandic sentence is a little broader than one single English phrasing.

Yes, but it would change the meaning.

• Strætóinn fer suður núna = The bus goes/is going south now
• Strætó fer suður núna = A bus / buses / bus goes south now, depending on context

Without the definite article, the noun is less specific. In real usage, context decides whether it sounds like a bus, bus traffic, or a more general statement.

Yes. Using words like suður, norður, austur, and vestur after verbs of motion is very normal.

For example:

• fara suður = go south
• keyra norður = drive north
• sigla vestur = sail west

So fer suður is completely natural Icelandic.

Three especially important things:

1. The definite article is attached to the noun

   • strætóinn = the bus

2. The verb is conjugated

   • fer comes from fara

3. Direction is expressed with a bare adverb

   • suður = southward / to the south

So this short sentence shows three very common Icelandic patterns at once.