La veu de la nova actriu és tan tranquil·la que tothom fa silenci quan parla.

Because tranquil·la describes la veu (the voice), and veu is a feminine singular noun in Catalan.

So the adjective has to agree with the noun:

• tranquil = masculine singular
• tranquil·la = feminine singular
• tranquils = masculine plural
• tranquil·les = feminine plural

Here the structure is:

• La veu = feminine singular
• és tranquil·la = is calm/quiet/soothing

Even though the voice belongs to the actress, the adjective agrees with voice, not with actress.

Tan ... que means so ... that.

In this sentence:

• és tan tranquil·la que...
• is so calm/quiet that...

This is a very common Catalan pattern:

• tan + adjective + que
• so + adjective + that

Examples:

• És tan alt que toca el sostre. = He is so tall that he touches the ceiling.
• Parla tan fluix que no el sento. = He speaks so softly that I can’t hear him.

So in your sentence, tan tranquil·la que introduces the result of the calm voice.

Because tothom means everyone / everybody, and in Catalan it is grammatically singular.

So you say:

• tothom fa = everyone does
• not tothom fan

This works like English everyone is, everybody says, even though it refers to many people.

More examples:

• Tothom ho sap. = Everyone knows it.
• Tothom arriba tard. = Everyone arrives late.

Yes, fer silenci is a normal Catalan expression.

Literally:

• fer = to make / do
• silenci = silence

So tothom fa silenci literally means everyone makes silence, but in natural English it means:

• everyone falls silent
• everyone becomes quiet
• everyone keeps quiet

Catalan often uses fer in expressions where English uses a different verb.

Other examples:

• fer una pregunta = to ask a question
• fer por = to be scary / to cause fear
• fer pena = to make someone feel sorry / to be pitiful

The subject is understood rather than stated. Catalan often leaves subject pronouns out because the verb form already gives enough information.

• parla = he/she speaks

In context, quan parla most naturally means when she speaks, referring to la nova actriu.

So the idea is:

• The voice of the new actress is so calm that everyone falls silent when she speaks.

Catalan does not need to say quan ella parla unless the speaker wants emphasis or contrast.

Because Catalan is a pro-drop language, like Spanish or Italian. Subject pronouns are often omitted when the verb ending makes the person clear enough.

So Catalan commonly says:

• parlo = I speak
• parles = you speak
• parla = he/she speaks

Instead of:

• jo parlo
• tu parles
• ell/ella parla

The pronoun is usually added only for emphasis, contrast, or clarity.

So quan parla is perfectly natural and means when he/she speaks, with the exact person understood from context.

Yes. De la nova actriu means of the new actress.

The phrase breaks down like this:

• de = of
• la = the
• nova = new
• actriu = actress

So:

• La veu de la nova actriu = The voice of the new actress

Catalan often uses de in places where English might use of or a possessive structure.

For example:

• el cotxe del meu amic = my friend’s car / the car of my friend
• la casa de la Maria = Maria’s house

So here de la nova actriu is just the normal way to show whose voice it is.

Because the feminine form of actor in Catalan is actriu.

So:

• actor = actor
• actriu = actress

This is a standard word pair, even though the feminine form is not made just by adding -a.

Some nouns in Catalan form the feminine in less predictable ways, so this is a word worth learning as a set:

• actor / actriu

Both are definite articles meaning the.

• La veu = The voice
• la nova actriu = the new actress

Catalan uses articles very regularly, and nouns usually need an article unless there is some other determiner or the context is more general.

Also, the article agrees in gender and number:

• el = masculine singular
• la = feminine singular
• els = masculine plural
• les = feminine plural

Since both veu and actriu are feminine singular nouns, they take la.

The dot in l·l is called the punt volat. It shows that this is a geminated l, not the ll sound.

So:

• ll in Catalan is usually a sound like the lli in some pronunciations of million
• l·l means the two l sounds are pronounced separately

So tranquil·la is pronounced roughly like:

• tran-kee-la, with a clear l + l sequence

The dot helps distinguish words like:

• col·legi = school from forms with ll, which would be pronounced differently.

For a learner, the important point is: tranquil·la does not have the same sound as Catalan ll.

In this sentence, veu is clearly the noun voice.

• La veu = the voice

But yes, veu can also be a verb form of veure (to see):

• ell/ella veu = he/she sees

Context tells you which meaning is intended.

Here, because it comes after the article la, it has to be a noun:

• La veu = The voice

Catalan adjectives can come after or sometimes before the noun, depending on the adjective and the nuance.

Here:

• la nova actriu

is very natural and means the new actress.

With some common adjectives like nou/nova, vell/vella, bon/bona, position can vary, but putting the adjective before the noun is often normal and can sound more descriptive or fixed.

In many cases, both orders are possible, though they may sound slightly different:

• la nova actriu
• l’actriu nova

For a learner, the key thing is that la nova actriu is a standard, natural phrase.

Not naturally in this sentence. Grammatically, parla could mean he/she speaks or sometimes it speaks, but context matters.

Here the sentence is about:

• the voice of the new actress

A voice does not normally speak by itself; the actress speaks. So the understood subject is she.

That means:

• quan parla = when she speaks

Catalan often relies on context to make this clear, just as English sometimes does.