No acerques la mano al cerdo hasta que la granjera te diga que está tranquilo.

Because this is a negative tú command.

In Spanish, negative commands for tú use the present subjunctive:

• acercas = you bring / you move closer
• no acerques = don’t bring / don’t move closer

So:

• Acerca la mano = Bring your hand closer.
• No acerques la mano = Don’t bring your hand closer.

That is a very common pattern:

• No hables = Don’t speak.
• No comas = Don’t eat.
• No salgas = Don’t go out.

It comes from the verb acercar.

To form the present subjunctive, you start from the yo form of the present indicative:

• yo acerco

Then remove -o and add the -ar subjunctive ending:

• acerqu- + es = acerques

The spelling changes from c to qu so that the hard k sound is kept before e.

Compare:

• acercar
• yo acerco
• que tú acerques

This is just a spelling rule, like:

• buscar → busques
• tocar → toques

Spanish often uses the definite article instead of a possessive with body parts, especially when it is already obvious whose body part it is.

So Spanish prefers:

• Levanta la mano = Raise your hand.
• Me duele la cabeza = My head hurts.
• No acerques la mano = Don’t bring your hand close.

Using tu mano is possible, but it sounds more emphatic or contrastive, as if you were stressing your hand rather than someone else’s.

Here acercar means to move something closer or to bring something near something else.

The structure is:

• acercar algo a algo/alguien = to bring something closer to something/someone

So:

• la mano = the thing being moved
• al cerdo = toward the pig / close to the pig

This does not necessarily mean touching the pig. It means bringing the hand near it.

If Spanish wanted to focus on touching, it might use a different verb, such as tocar.

Because al is the contraction of a + el.

• a el cerdo → al cerdo

This is required in normal Spanish whenever a is followed by el.

So:

• Voy al mercado = I’m going to the market.
• Acerca la silla al fuego = Bring the chair closer to the fire.
• No acerques la mano al cerdo = Don’t bring your hand close to the pig.

This is not the personal a here. It is just the preposition a used with acercar.

Because hasta que is followed by the subjunctive when the action is in the future or has not happened yet.

In this sentence, the speaker is talking about a future condition:

• first, do not bring your hand near the pig
• then, wait until the farmer tells you something

That telling has not happened yet, so Spanish uses the subjunctive:

• hasta que la granjera te diga

Compare:

• Espera aquí hasta que vuelva = Wait here until he/she comes back.
• No salgas hasta que termine = Don’t go out until it finishes.
• No acerques la mano al cerdo hasta que la granjera te diga...

If the action is habitual or already viewed as a fact, Spanish can use the indicative, but not in this sentence.

Te means to you.

The verb decir often works like this:

• decir algo a alguien = to tell something to someone

So in the sentence:

• la granjera = the farmer
• te = to you
• diga = tells
• que está tranquilo = that it is calm

So literally:

• until the female farmer tells you that it is calm

Examples:

• Te digo la verdad = I tell you the truth.
• La profesora te dice la respuesta = The teacher tells you the answer.

Good question. The first verb is subjunctive because of hasta que and the future, unfinished situation:

• hasta que la granjera te diga

But after decir que, Spanish normally uses the indicative for the content of what is being said, if it is presented as a statement:

• te diga que está tranquilo = tells you that it is calm

So:

• diga = subjunctive because of the structure with hasta que
• está = indicative because it is the content of the message

Compare:

• Espero que venga = I hope he comes.
  Here venga is subjunctive because esperar que triggers it.
• Me dice que viene = He tells me that he is coming.
  Here viene is usually indicative because it is reported information.

It refers to el cerdo.

So the idea is:

• Don’t bring your hand near the pig until the female farmer tells you that the pig is calm.

Even though cerdo is not repeated, Spanish understands it from the context.

Also, tranquilo is masculine singular, which matches cerdo:

• cerdo → masculine singular
• tranquilo → masculine singular

If it referred to la granjera, it would have to be tranquila.

Yes, depending on context, tranquilo can mean:

• calm
• quiet
• peaceful
• settled

Here, with an animal that you should not approach yet, calm is the most natural meaning.

So it suggests the pig is no longer agitated, stressed, or likely to react badly.

Yes.

• granjero = male farmer
• granjera = female farmer

Since the sentence is talking about a female farmer, it uses la granjera.

A learner may also notice that in English farmer does not usually show gender, but Spanish often does:

• el profesor / la profesora
• el camarero / la camarera
• el granjero / la granjera

Here it is simply the normal noun pig.

But yes, cerdo can also be used as an insult, a bit like pig in English, meaning someone is dirty, disgusting, or gross.

In this sentence, though, it clearly means the animal because of the context.

It is:

• No acerques = negative command to tú
• la mano = direct object
• al cerdo = complement showing where/toward what the hand is being moved

So, very literally:

• Don’t bring the hand toward the pig

More natural English:

• Don’t bring your hand near the pig

Yes, but it means something different.

• No acerques la mano al cerdo = Don’t bring your hand near the pig.
• No te acerques al cerdo = Don’t go near the pig / Don’t approach the pig.

The first focuses specifically on the hand. The second focuses on you approaching the pig.

So they are related, but not interchangeable.

Yes, but only in different kinds of contexts.

Use subjunctive after hasta que when the action is still pending or future:

• Espera hasta que llegue = Wait until he arrives.

Use indicative when referring to a habitual action or something already seen as real/factual:

• Siempre espero hasta que llega = I always wait until he arrives.

In your sentence, the farmer has not told you yet, so Spanish uses:

• hasta que la granjera te diga

It could be repeated:

• ...hasta que la granjera te diga que el cerdo está tranquilo

That version is clearer and more explicit.

But Spanish often leaves out things that are already obvious from context. Since the pig has just been mentioned, que está tranquilo is perfectly natural.

So:

• que está tranquilo = natural, less repetitive
• que el cerdo está tranquilo = more explicit

Both are correct.

Yes, it sounds natural and standard.

A speaker from Spain would easily understand it. The grammar is normal, and the vocabulary is standard.

A few small variations could also be natural depending on style, for example:

• No acerques la mano al cerdo hasta que la granjera te diga que ya está tranquilo.
• No le acerques la mano al cerdo hasta que la granjera te diga que está tranquilo.

But the original sentence is already perfectly good Spanish.