¿Qué quieres de postre?

Because qué is an interrogative word in this sentence: it means what in a question.

In Spanish, question words like qué, cuándo, dónde, cómo, cuál usually take an accent when they are used in direct or indirect questions.

• ¿Qué quieres de postre? = What do you want for dessert?
• But: Lo que quieres = what you want
  Here que does not have an accent because it is not being used as a question word.

Spanish uses double question marks:

• ¿ at the beginning
• ? at the end

So the full question is written as:

• ¿Qué quieres de postre?

This helps show from the start that the sentence is a question.

Quieres is the tú form of the verb querer, which usually means to want.

Present tense of querer:

• yo quiero
• tú quieres
• él/ella/usted quiere
• nosotros queremos
• vosotros queréis
• ellos/ellas/ustedes quieren

So quieres is used because the speaker is talking to you informally, singular:

• ¿Qué quieres de postre? = speaking to one person you know or are addressing informally.

Also note that querer is a stem-changing verb:

• quer- becomes quier- in several forms
  So not tú queres, but tú quieres.

In Spanish, subject pronouns are often left out because the verb ending already shows who the subject is.

• quieres already tells you the subject is tú

So:

• ¿Qué quieres de postre? is natural
• ¿Qué tú quieres de postre? is not the normal wording here

You can say:

• ¿Qué quieres tú de postre?

But adding tú usually gives emphasis, as if contrasting with someone else:

• I know what I want, but what do you want for dessert?

Postre means dessert.
The phrase de postre is a very common way to mean for dessert.

Literally, de often means of/from, but in many fixed expressions it is translated differently in English. Here:

• de postre = for dessert / as dessert

So Spanish says:

• ¿Qué quieres de postre?

where English says:

• What do you want for dessert?

This is just the natural Spanish expression. You should learn de postre as a set phrase.

Yes, you may hear para postre, and it can be understood, but de postre is the more standard and idiomatic expression in this context.

Most learners should use:

• ¿Qué quieres de postre?

Similarly:

• Tomamos fruta de postre = We’re having fruit for dessert

So if you want the most natural everyday phrasing, de postre is the safer choice.

It is informal, because it uses quieres, the tú form.

If you wanted to ask the same thing more formally, you would say:

• ¿Qué quiere de postre?

That uses usted language, even though usted itself is usually omitted.

In Spain, tú is very common in everyday situations, but with strangers, older people, or in more formal service situations, usted may still be used depending on context and region.

In Spain, if you are speaking informally to more than one person, you would use vosotros:

• ¿Qué queréis de postre?

If you are being formal with more than one person:

• ¿Qué quieren de postre?

In Latin America, ustedes is normally used for plural you, even in informal situations:

• ¿Qué quieren de postre?

So ¿Qué queréis de postre? is especially useful for Spain.

A natural neutral pronunciation would stress the important content words:

• ¿QUÉ quieres de posTRE?

A few pronunciation notes:

• qué sounds roughly like keh
• quieres begins with kye-
• postre has two syllables: POS-tre, with stress on the first syllable

Because qué is the question word, it often gets clear emphasis at the start.

No. In this everyday context, querer is the normal verb for want.

So in a restaurant or at home, ¿Qué quieres de postre? sounds completely natural.

Spanish querer can sometimes mean to love when used with people:

• Te quiero

But in this sentence, with a thing like postre, it simply means want.

Yes, absolutely. It sounds natural and common.

You might hear it:

• at home after a meal
• in a restaurant
• when offering choices

Other very natural alternatives include:

• ¿Qué quieres de postre hoy? = What do you want for dessert today?
• ¿Vas a tomar postre? = Are you going to have dessert?
• ¿Qué te apetece de postre? = What do you feel like for dessert?

But ¿Qué quieres de postre? is a perfectly normal everyday sentence.

A few simple answers are:

• Quiero helado. = I want ice cream.
• Quiero fruta. = I want fruit.
• Tarta, por favor. = Cake, please.
• Nada, gracias. = Nothing, thanks.
• ¿Qué hay de postre? = What is there for dessert?

In casual conversation, you do not always need the full sentence:

• Helado.
• Fruta.
• Nada para mí.