Vil De have et glas vand?

De is the old-fashioned or formal you in Danish, and it is traditionally capitalized to show respect. In modern everyday Danish, people usually say du instead.

So:

• Vil De have et glas vand? = formal / polite / somewhat old-fashioned
• Vil du have et glas vand? = normal everyday speech

You may still see De in very polite service situations, historical writing, or older texts.

Here, De means you.

It is:

• second person
• usually singular when speaking politely to one person
• sometimes also used in a formal plural sense, depending on context

For most learners, the important point is: in this sentence, De is simply the formal version of you.

Not exactly, even though the words are related historically.

In this sentence, vil means something more like:

• want to
• would like to

So Vil De have et glas vand? is not really Will you have a glass of water? in the future sense. It is more like:

• Would you like a glass of water?
• Do you want a glass of water?

Danish ville/vil often expresses desire or willingness, not just future time.

Because after the modal verb vil, Danish uses the infinitive without at.

So:

• vil have = want to have
• not vil at have

This is similar to English modal verbs:

• I can go, not I can to go
• I will eat, not I will to eat

Common Danish modal verbs that also take the infinitive without at include:

• kan = can
• skal = must / will
• må = may / must
• vil = want to / will

Because this is a yes/no question.

In Danish, yes/no questions usually have verb-first word order. That means the finite verb comes before the subject.

Compare:

• De vil have et glas vand. = You want a glass of water.
• Vil De have et glas vand? = Would you like a glass of water?

This is very similar to English:

• You want...
• Do you want...? / Would you like...?

Danish often forms questions by inversion rather than by adding a helper like do.

Because glas is a neuter noun in Danish, so it takes et in the indefinite singular.

Danish nouns have two grammatical genders:

• en-words (common gender)
• et-words (neuter)

So:

• et glas = a glass
• glasset = the glass

You just have to learn the gender of each noun along with the noun itself.

In Danish, et glas vand literally means a glass water, but it naturally corresponds to English a glass of water.

Danish often expresses this kind of quantity phrase without a word for of:

• et glas vand = a glass of water
• en kop kaffe = a cup of coffee
• en flaske vin = a bottle of wine

So this structure is completely normal in Danish.

Yes, but in this context it is often understood more naturally as to have / to take / to want something in the sense of receiving it.

So Vil De have et glas vand? is an offer. It is not really about possession in a strict sense. In English, we might translate it as:

• Would you like a glass of water?
• Do you want a glass of water?
• Would you care for a glass of water?

So the Danish verb is have, but the natural English meaning depends on context.

It is grammatically correct, but it sounds formal and possibly old-fashioned in many modern situations because of De.

A more common modern version would be:

• Vil du have et glas vand?

If you are talking to friends, family, classmates, coworkers, or most strangers in Denmark today, du is usually the normal choice.

A careful approximation is:

• Vil De have et glas vand?
• roughly: vil dee HAY-və ed glass vann?

A few useful pronunciation notes:

• vil sounds roughly like vil
• De sounds like dee
• have is often pronounced something like ha-ve or hæ-ve, depending on accent and speaking style
• et is often reduced in speech, sometimes sounding almost like a soft e or ed
• vand has a soft Danish d, so it does not sound exactly like English vand

As always, actual Danish pronunciation is smoother and more reduced than the spelling suggests.

Yes, you could, but it sounds more formal and less conversational.

• Vil De have et glas vand? = natural polite offer
• Ønsker De et glas vand? = more formal, service-like, or written-sounding

In everyday conversation, vil ... have is usually more natural than ønsker.

Some simple answers are:

• Ja, tak. = Yes, please.
• Nej, tak. = No, thank you.

You could also say:

• Ja, gerne. = Yes, gladly / Yes, please.
• Nej tak, ellers tak. = No thanks, but thanks anyway.

If you want to stay at the same formal level, you can do so, but in modern Danish, short polite replies like Ja, tak and Nej, tak are completely normal.