Var är min nyckel? Jag behöver den nu.

In Swedish, direct questions usually put the verb before the subject, just like English does in Where is my key?

So:

• Var = where
• är = is
• min nyckel = my key

That gives Var är min nyckel?

The order Var min nyckel är sounds like a subordinate clause, as in:

• Jag vet inte var min nyckel är. = I don’t know where my key is.

So the sentence in your example is using normal direct-question word order.

When you use a possessive like min (my), Swedish normally does not add the definite ending to the noun.

So:

• min nyckel = my key
• nyckeln = the key

You usually choose one or the other:

• min nyckel = my key
• nyckeln = the key

Using both together in this basic pattern would be wrong.

Because nyckel is a common gender noun in Swedish, not a neuter noun.

Swedish has two grammatical genders:

• en-words → referred to with den
• ett-words → referred to with det

Nyckel is an en-word:

• en nyckel = a key

So when replacing it with it, you use den:

• Jag behöver nyckeln.
• Jag behöver den nu.

If the noun were an ett-word, you would use det instead.

Yes, den can mean different things depending on context.

In this sentence, den is a pronoun replacing nyckel, so it means it:

• Jag behöver den nu. = I need it now.

But den can also be used in other ways, including as part of expressions that mean that.

So the important thing is to look at its function in the sentence. Here, it clearly stands for nyckel, so it is the natural translation.

Because Swedish does not use an indefinite article together with a possessive.

Compare:

• en nyckel = a key
• min nyckel = my key

You do not say en min nyckel.

This is similar to English: you say my key, not a my key.

Yes. Var är nyckeln? means Where is the key?

The difference is:

• Var är min nyckel? = Where is my key?
• Var är nyckeln? = Where is the key?

So the first one emphasizes possession, while the second just uses the definite noun.

That is a very normal Swedish word order.

The basic structure is:

• Jag = subject
• behöver = verb
• den = object
• nu = time expression

So:

• Jag behöver den nu. = I need it now.

Putting nu at the end is natural and common. Swedish often places short time words like nu after the object.

You can sometimes move things around for emphasis, but the version in your sentence is the most neutral one.

Behöver is the present tense of behöva (to need).

So:

• behöva = to need
• behöver = need / am needing

In this sentence:

• Jag behöver den nu. = I need it now.

Swedish present tense does not change by person, so the same form is used with all subjects:

• jag behöver
• du behöver
• han/hon behöver
• vi behöver

Yes. Behöva can take a direct object, just like English need.

Examples:

• Jag behöver hjälp. = I need help.
• Hon behöver bilen. = She needs the car.
• Jag behöver den nu. = I need it now.

So this sentence is completely straightforward grammatically: the verb behöver is followed by the pronoun den.

Because var is used for location, while vart is used for direction.

• Var är min nyckel? = Where is my key?
  (location: where is it?)
• Vart går du? = Where are you going?
  (direction: where to?)

Since the sentence asks about the key’s location, var is the correct choice.

A rough guide is NICK-el, but with a Swedish y sound, which does not exist exactly in English.

A few tips:

• ny is not like English new
• the y is a rounded front vowel; you make an ee-like sound while rounding your lips
• ck sounds like k
• the stress is on the first syllable: NYCK-el

So it is something like NYK-el, but with Swedish vowel quality.

A rough pronunciation guide:

• är ≈ air, though the vowel quality is Swedish
• behöver has stress on the second syllable: be-HÖ-ver

For behöver:

• be is light and unstressed
• hö contains the Swedish ö sound
• ver is softer than a strongly pronounced English ver

A rough English-friendly guide might be:

• är ≈ air
• behöver ≈ be-HUR-ver / be-HER-ver, but neither is exact

If pronunciation is important for you, ö and y are two vowel sounds worth practicing early, because English does not match them closely.

It is a very natural and correct way to say it.

But Swedish can also choose other wording depending on tone and context. For example:

• Jag behöver den nu. = I need it now.
• Jag måste ha den nu. = I have to have it now.

Your original sentence is neutral and idiomatic. It is exactly the kind of sentence a learner should remember as a solid model.