Nýja sjónvarpið kostaði sjötíu þúsund, svo ég geymi kassann enn í geymsluhólfinu.

Because sjónvarpið is definite: it means the TV.

In Icelandic, when a noun is definite, the adjective usually takes the weak form. So:

• nýtt sjónvarp = a new TV
• nýja sjónvarpið = the new TV

Here:

• sjónvarp is a neuter noun
• sjónvarpið is the TV
• nýja is the weak neuter singular form of nýr

So nýja sjónvarpið is the correct way to say the new TV.

It has two parts:

• sjónvarp = television / TV
• -ið = the suffixed definite article for a neuter singular noun

So:

• sjónvarp = a TV
• sjónvarpið = the TV

This is very common in Icelandic: instead of a separate word like the, Icelandic often adds the article to the end of the noun.

Kostaði is the past tense of kosta, meaning to cost.

The sentence is talking about what the TV cost when it was bought, so past tense makes sense:

• kosta = to cost
• kostar = costs
• kostaði = cost

So sjónvarpið kostaði sjötíu þúsund means that the TV cost seventy thousand.

It literally means seventy thousand:

• sjötíu = seventy
• þúsund = thousand

In everyday Icelandic, if the context is buying something, the currency is often understood to be krónur unless something else is stated. So this usually means seventy thousand krónur.

Because Icelandic often leaves the currency unstated when it is obvious from context.

If someone says an item kostaði sjötíu þúsund, listeners will normally understand Icelandic krónur.

You could say sjötíu þúsund krónur, but it is very natural to omit krónur here.

Here svo means so or therefore.

It connects the two ideas:

• the TV was expensive
• therefore, the speaker is still keeping the box

So in this sentence, svo is showing a result or consequence.

Depending on context, svo can also mean things like then, and then, or thus, but here so is the best fit.

Because the two clauses refer to different times:

• kostaði = what the TV cost in the past
• geymi = what the speaker still does now

So the sentence means:

• the TV cost a lot back then
• as a result, I still keep the box now

This tense combination is completely natural in Icelandic, just as it is in English.

Because kassann is the direct object of geymi, and geyma takes the accusative case.

The noun is kassi = box. Its singular definite forms include:

• kassinn = the box, nominative
• kassann = the box, accusative
• kassanum = the box, dative

Since the speaker is keeping the box, the box is the object of the verb, so accusative is needed:

• ég geymi kassann = I keep the box

Enn here means still.

So ég geymi kassann enn means I still keep the box.

Its position is fairly natural in Icelandic. Adverbs like enn can move around somewhat depending on emphasis, but this placement is very normal:

• ég geymi kassann enn í geymsluhólfinu

The idea is that the speaker has not thrown it away yet.

Because í can take either:

• accusative for movement into
• dative for location in

Here the box is already located there, so this is location, not movement. That is why Icelandic uses the dative:

• í geymsluhólfinu = in the storage compartment

Compare:

• Ég set kassann í geymsluhólfið. = I put the box into the storage compartment.
  
  • movement, so accusative
• Kassinn er í geymsluhólfinu. = The box is in the storage compartment.
  
  • location, so dative

It is a compound noun plus the definite ending.

Breakdown:

• geymsla = storage
• hólf = compartment / cubby / small enclosed space
• geymsluhólf = storage compartment
• geymsluhólfinu = the storage compartment in the dative singular

So the word is basically storage-compartment-the, in the form required by í for location.

Yes. Icelandic uses compound words very freely.

A lot of vocabulary is built this way:

• sjón + varp → sjónvarp
• geymslu + hólf → geymsluhólf

For English speakers, it helps to get used to reading Icelandic compounds as smaller meaningful pieces joined together.

Because the sentence joins two full clauses:

• Nýja sjónvarpið kostaði sjötíu þúsund
• svo ég geymi kassann enn í geymsluhólfinu

Using a comma before svo is normal Icelandic punctuation here, especially when the second clause expresses a result.

Yes, to a degree.

The sentence as written is very natural:

• ..., svo ég geymi kassann enn í geymsluhólfinu.

But Icelandic word order is somewhat flexible, especially with adverbs. For example, enn could appear in a slightly different position depending on emphasis.

Still, not every rearrangement sounds equally natural, and Icelandic follows important word-order rules, especially in main clauses. So for a learner, the sentence as given is a very good model to copy.

Yes, sjónvarp is a neuter noun.

That matters because it affects:

• the adjective form: nýja
• the definite noun form: sjónvarpið

If it were a masculine or feminine noun, those forms would look different.

Here are the main dictionary forms:

• nýr = new
• sjónvarp = television / TV
• kosta = to cost
• sjötíu = seventy
• þúsund = thousand
• svo = so / therefore
• ég = I
• geyma = to keep / store
• kassi = box
• enn = still
• í = in / into
• geymsluhólf = storage compartment

This is useful because many of the words in the sentence appear in inflected forms rather than their dictionary forms.