Við þurfum að pakka í kvöld, því ferðataskan mín er enn tóm.

Because við means we, and þurfum is the 1st person plural present form of þurfa (to need / must).

So:

• ég þarf = I need
• þú þarft = you need
• við þurfum = we need

The verb changes to match the subject, just as English changes am / is / are, though Icelandic does this more often.

Here að is the infinitive marker, like English to in to pack.

So:

• pakka = pack
• að pakka = to pack

After þurfa, Icelandic normally uses að + infinitive:

• Við þurfum að fara = We need to go
• Við þurfum að pakka = We need to pack

So the structure is very similar to English need to + verb.

Yes. In this sentence, að pakka means something like to do the packing or to pack our things. Icelandic, like English, can leave the object unstated when it is obvious from context.

So Við þurfum að pakka naturally means We need to pack even though it does not say exactly what is being packed.

Í kvöld means tonight / this evening.

Literally, it looks like in evening, but as a fixed time expression it is used the way English uses tonight.

This is a very common Icelandic pattern:

• í dag = today
• í morgun = this morning
• í kvöld = tonight / this evening

So you should learn í kvöld as a set expression.

Here því means because.

It introduces the reason:

• Við þurfum að pakka í kvöld = We need to pack tonight
• því ferðataskan mín er enn tóm = because my suitcase is still empty

So the whole sentence means that the second clause explains the first one.

A learner should know that því can also be another word in other contexts, but here it is a conjunction meaning because.

Because Icelandic often puts the definite article onto the end of the noun instead of using a separate word.

So:

• ferðataska = suitcase
• ferðataskan = the suitcase

This final -n is the definite article here.

That is a very important Icelandic pattern:

• bók = book
• bókin = the book

So ferðataskan mín literally looks like the suitcase my, but it means my suitcase.

The most natural neutral word order in Icelandic is often:

noun + definite article + possessive

So:

• ferðataskan mín = my suitcase
• bókin mín = my book
• húsið mitt = my house

The version mín ferðataska is possible, but it is usually more marked, more emphatic, or more contrastive, something like my suitcase as opposed to someone else’s.

So if you are just saying my suitcase in an ordinary way, ferðataskan mín is the normal choice.

Because possessive words in Icelandic agree with the noun they describe in gender, number, and case.

The noun ferðataska is feminine singular, and here it is in the nominative, so the correct form is mín.

Compare:

• minn bíll = my car (bíll is masculine)
• mín taska / taskan mín = my bag (taska is feminine)
• mitt hús = my house (hús is neuter)

So mín is used because ferðataskan is feminine.

Here enn means still.

So:

• er enn tóm = is still empty

It shows that the suitcase was empty before, and it continues to be empty now.

This is different from ekki enn, which means not yet:

• Hún er ekki komin enn = She has not arrived yet

So in your sentence, enn is simply still.

Because adjectives in Icelandic agree with the noun they describe.

The subject is ferðataskan mín, which is feminine singular nominative, so the adjective must match that:

• masculine: tómur
• feminine: tóm
• neuter: tómt

That is why the sentence has:

• ferðataskan mín er enn tóm

not tómur or tómt.

Yes. In the clause ferðataskan mín er enn tóm, the subject is ferðataskan mín.

The structure is:

• ferðataskan mín = subject
• er = is
• enn tóm = still empty

So this clause works very much like English my suitcase is still empty.

Because in normal Icelandic word order, an adverb like enn commonly comes before the adjective it modifies.

So:

• er enn tóm = is still empty

This is the natural order. It is the same kind of idea as English still empty, where still comes before the adjective empty.