Þau flytja inn á morgun.

Þau means they, but specifically the neuter plural form of they.

In Icelandic, they has different forms depending on grammatical gender:

• þeir = they (masculine)
• þær = they (feminine)
• þau = they (neuter)

Þau is often used:

• for a group of people that includes different genders
• for children
• for neuter plural nouns

So in this sentence, þau most likely means they referring to a mixed group or a context where neuter is appropriate.

Because Icelandic distinguishes they by gender.

A native English speaker is used to just one form, they, but Icelandic requires you to choose:

• þeir for a masculine group or a mixed group in many contexts
• þær for an all-feminine group
• þau for neuter groups, children, or sometimes people when the context calls for the neuter form

So the sentence uses þau because the speaker is referring to a group understood as neuter in context. Without more context, you cannot tell exactly why, only that þau is the form chosen.

Here, flytja is the present tense, 3rd person plural form of the verb.

So:

• ég flyt = I move
• þú flytur = you move
• hann/hún/það flytur = he/she/it moves
• við flytjum = we move
• þið flytjið = you all move
• þau flytja = they move

A useful thing to notice is that the infinitive is also flytja, so the dictionary form and the they form look the same.

Because flytja inn works like a kind of phrasal verb and means move in.

Compare:

• flytja = move, transport, relocate
• flytja inn = move in
• flytja út = move out

So inn adds the idea of movement into a home or place.

This is similar to English:

• They move tomorrow
• They move in tomorrow

That small extra word changes the meaning.

Not always. Flytja inn can also mean import, depending on context.

For example:

• with people and a time phrase like this, it usually means move in
• with goods or products, it can mean import

So context tells you which meaning is intended. In this sentence, it is understood as move in.

Á morgun means tomorrow.

Literally, it looks like on morning/tomorrow, but you should learn it as a fixed Icelandic expression meaning tomorrow.

The preposition á is just the normal one used in this expression. English speakers often want to translate word-for-word, but here it is better to remember:

• á morgun = tomorrow
• í morgun = this morning / earlier today

That contrast is very important, because learners often mix them up.

In á morgun, morgun is in the accusative.

This is part of the fixed time expression. Even if you do not know all the case rules yet, it is useful to memorize the whole phrase:

• á morgun = tomorrow

At an early stage, treating it as one chunk is often the easiest approach.

No, not necessarily. Á morgun usually means tomorrow in general, not specifically the morning.

If you want to be more specific, Icelandic can say things like:

• á morgun morgun? No, that is not the normal way.
• more naturally, the sentence would be clarified with context or another expression if the speaker really means the morning part of the day

So in your sentence, á morgun should normally be understood as tomorrow, not tomorrow morning.

Yes. Icelandic word order is flexible, but it follows a strong verb-second tendency in main clauses.

The basic sentence is:

• Þau flytja inn á morgun.

You can also front the time expression:

• Á morgun flytja þau inn.

That still means the same thing, but now á morgun is emphasized a bit more.

Notice what happens:

• when á morgun comes first,
• the finite verb flytja comes next,
• then the subject þau follows

That verb-second pattern is very common in Icelandic.

It often stays separate from the verb, much like a particle.

For example:

• Þau flytja inn á morgun. = They are moving in tomorrow.
• Þau flytja ekki inn á morgun. = They are not moving in tomorrow.
• Flytja þau inn á morgun? = Are they moving in tomorrow?

So you should think of inn as a separate word that belongs with the verb meaning, not as an ending attached to the verb.

A rough learner-friendly pronunciation is:

THöy FLIT-ya in ow MOR-gun

A few important sounds:

• þ = the th sound in thin
• au = roughly like the vowel in öy or something similar to oy, though not exactly English oy
• y in flytja is not an English y sound; it is a vowel
• j in flytja sounds like English y in yes

So flytja is roughly FLIT-ya, not fly-ja.

Not exactly.

• Þau flytja á morgun would mean something more like they move tomorrow or they are relocating tomorrow
• Þau flytja inn á morgun specifically means they move in tomorrow

So inn is important because it adds the idea of moving into a place, especially a new home or apartment.