Vull signar l'acord.

Because Catalan often drops the subject pronoun when it is clear from the verb ending.

• vull already means I want
• so Vull signar l'acord is perfectly natural

You can add jo for emphasis or contrast:

• Jo vull signar l'acord, però ell no.
  I want to sign the agreement, but he doesn’t.

So in normal sentences, leaving out jo is very common.

Vull is the 1st person singular present indicative of the verb voler (to want).

So:

• vull = I want

This verb is irregular, so you cannot guess vull from the infinitive voler in a simple way. It is a form you need to learn as part of the verb.

After voler (to want), Catalan normally uses another verb in the infinitive:

• vull signar = I want to sign
• vols venir = you want to come
• volem marxar = we want to leave

This is similar to English want to + verb, except Catalan does not use a separate word equivalent to to here.

So:

• vull signar
• literally: I want sign
• natural English: I want to sign

L' is the definite article that appears before a vowel sound.

Here, acord is a masculine singular noun, so its article is el. But before a vowel, el becomes l':

• el llibre = the book
• l'acord = the agreement

So:

• el + acord becomes l'acord

This apostrophe is very common in Catalan.

You have to know the gender of the noun.

• if the noun is masculine singular, l' stands for el
• if the noun is feminine singular, l' stands for la

In this sentence:

• acord is masculine
• so l'acord = el acord -> contracted to l'acord

Examples:

• l'amic = el amic -> the male friend
• l'amiga = la amiga -> the female friend

So l' by itself does not show gender; the noun does.

Because signar normally takes a direct object in Catalan.

• signar l'acord
• signar el contracte
• signar un document

English also says sign the agreement, not sign to the agreement in this context.

So l'acord is simply the object of signar.

This is the normal, neutral word order:

• Vull = verb
• signar = infinitive
• l'acord = object

Catalan often uses this kind of structure very naturally.

You may also hear other orders in special contexts for emphasis, but Vull signar l'acord is the standard, straightforward version.

Yes, firmar also exists and is commonly used in many contexts for to sign.

However, signar is also perfectly correct and often feels more standard or formal, especially in writing.

So both can be possible depending on region, style, and context:

• Vull signar l'acord
• Vull firmar l'acord

Both are understandable and natural.

A simple learner-friendly guide:

• vull sounds roughly like booly said very quickly, though the final ll is a Catalan sound and may vary by dialect
• l'acord sounds roughly like la-KORD

A few useful notes:

• Catalan v is usually pronounced like b
• the stress in acord is on the second syllable: a-CORD
• the apostrophe in l'acord does not create a pause; it flows together as one unit

If you want to sound natural, try saying the whole sentence smoothly:

• Vull signar l'acord

Put no before the conjugated verb:

• No vull signar l'acord. = I do not want to sign the agreement.

This is the normal way to negate the sentence in Catalan.

You would use the indefinite article:

• Vull signar un acord. = I want to sign an agreement.

So the difference is:

• l'acord = the agreement
• un acord = an agreement

This changes how specific the noun is. l'acord refers to a particular agreement, while un acord is more general.