Vostè vol que li posi el llibre sobre la taula?

Vostè is the formal singular way to say you in Catalan.

It is used:

• to be polite
• with strangers
• in more formal situations
• sometimes with older people or customers, depending on context

A very important point: although vostè means you, it takes third-person singular verb forms.

So:

• Tu vols... = informal you want...
• Vostè vol... = formal you want...

The plural formal form is vostès.

Because vostè uses third-person singular agreement.

So the verb behaves as if the subject were he/she grammatically, even though the meaning is you.

Compare:

• Tu vols que et posi el llibre...?
• Vostè vol que li posi el llibre...?

So:

• vols goes with tu
• vol goes with vostè

It can definitely be omitted.

Catalan often leaves out subject pronouns because the verb form usually gives enough information. So this sentence could also be:

Vol que li posi el llibre sobre la taula?

That sounds very natural.

Including vostè can:

• make the sentence a bit more explicit
• add politeness or emphasis
• help clarify who is being addressed

Here que introduces a subordinate clause.

Literally, Catalan says something like:

You want that I put the book on the table for you?

That sounds unnatural in English, but it is normal in Catalan.

After verbs like voler when one person wants another person to do something, Catalan usually uses:

voler + que + subjunctive

So:

• Vostè vol que...
• Do you want me to...?

Because after vol que, Catalan uses the subjunctive when the subject of the second verb is different from the subject of the first verb.

Here:

• Vostè vol = you want
• que jo posi = that I put

So posi is the present subjunctive of posar.

Why not posar? Because posar is the infinitive, and Catalan does not normally use the infinitive here when the person doing the second action is different.

Compare:

• Vostè vol posar el llibre...? = Do you want to put the book...?
  (same subject: you want, and you will put it)
• Vostè vol que li posi el llibre...? = Do you want me to put the book...?
  (different subject: you want, I will put it)

The subject is understood as jo = I.

So:

• que li posi el llibre = that I put the book for you / that I place the book for you

Catalan often drops subject pronouns, so jo is not stated.

A fuller version would be:

Vostè vol que jo li posi el llibre sobre la taula?

In normal speech, the jo is usually unnecessary.

Li is an indirect object pronoun. Here it means to you or for you, referring to vostè.

So:

• li posi el llibre = put the book for you / put the book to you
  In natural English: put the book for you or simply put the book

It does not mean it.

Compare:

• tu → et
• vostè → li (in this kind of indirect-object use)

So the formal version uses the third-person-style pronoun again.

Because Catalan object pronouns usually go before a conjugated verb.

So:

• li posi
• li dono
• li diré

That is the normal pattern.

You often see pronouns attached after the verb only with:

• infinitives: posar-li
• gerunds: posant-li
• affirmative commands: posi-li

But here posi is a finite subjunctive form inside a clause, so li goes before it:

• que li posi

Here it means on the table.

With posar, English might also naturally say onto the table, because the idea is moving something to that position.

So:

• posar el llibre sobre la taula = put the book on/onto the table

A useful note: sobre can also mean about/concerning in other contexts, but here it clearly expresses location.

Some speakers may also say:

• damunt la taula
• damunt de la taula

for a clearly physical sense of on top of the table.

Catalan does not need English-style do-support.

English says:

• Do you want me to put the book on the table?

Catalan can simply use the normal verb form plus question intonation and a question mark:

• Vostè vol que li posi el llibre sobre la taula?

So there is:

• no extra do
• no special inversion like in English

In writing, the final ? shows it is a question. In speech, intonation does the job.