El código PIN protege el número de teléfono.

Spanish uses the definite article el much more often than English does.

In El código PIN protege el número de teléfono:

• El código PIN = the PIN code
• el número de teléfono = the phone number

In English, you might sometimes drop the, depending on context, but in Spanish it is very normal to keep it with nouns like these.

Also, both código and número are masculine singular nouns, so they take el.

Protege is the conjugated verb.
Proteger is the infinitive, meaning to protect.

Here, the subject is El código PIN, which is third-person singular, so the verb must match it:

• proteger = to protect
• protege = it protects / he protects / she protects

So:

• El código PIN protege... = The PIN code protects...

The subject is El código PIN.

That is the thing doing the action.
The action is protege (protects).
The object receiving the action is el número de teléfono.

So the structure is:

• El código PIN = subject
• protege = verb
• el número de teléfono = direct object

In Spanish, the most natural way to say phone number is número de teléfono.

This is a very common Spanish structure:

• noun + de + noun

Here it literally means number of telephone, but in natural English we translate it as phone number.

Other similar examples:

• tarjeta de crédito = credit card
• mesa de cocina = kitchen table
• zapatos de deporte = sports shoes

So de is often used where English uses one noun directly before another.

The written accents show which syllable is stressed.

• código → stress on có
• número → stress on nú
• teléfono → stress on lé

Without the accent marks, Spanish pronunciation rules would make you stress a different syllable, so the accents are necessary.

These accents are part of the correct spelling, not optional marks.

In Spain, protege is pronounced approximately like:

pro-TE-he

A few points:

• g before e sounds like a strong throaty h sound in standard Spain Spanish.
• The stress is on the middle syllable: te.

So it is not pronounced like English pro-tej. The final sound is more like the j in Spanish jamón, but in the position before e.

Yes, in a strict literal sense it is redundant.

PIN comes from English Personal Identification Number, so saying código PIN is a bit like saying PIN code in English, which is also technically redundant.

But this redundancy is extremely common and natural in everyday language, both in English and Spanish. So código PIN is perfectly normal.

Because al is only used when a + el come together.

For example:

• Voy al banco = I go to the bank

In your sentence, there is no a before el número de teléfono, because proteger takes a direct object without a in this case:

• protege el número de teléfono

So there is no reason to contract anything.

Yes, but the meaning changes slightly.

• El código PIN protege el número de teléfono
  = The PIN code protects the phone number
  This sounds like a specific PIN code, or a general statement about the PIN code in a known context.

• Un código PIN protege el número de teléfono
  = A PIN code protects the phone number
  This is more indefinite.

Spanish articles matter a lot, just as the and a do in English, even if usage is not always identical.

Yes, Spanish often drops subject pronouns, but here the noun subject itself carries important information.

• Protege el número de teléfono by itself could mean:
  • He/she/it protects the phone number, or
  • as a command, depending on context and punctuation

So keeping El código PIN makes the sentence clear.

Spanish commonly drops pronouns like él, ella, ellos, but it does not usually drop a full noun subject if that noun is needed to identify who or what is doing the action.

Because the personal a is mainly used before specific people and sometimes pets or personified beings, not before ordinary things.

Compare:

• Veo el número de teléfono = I see the phone number
• Veo a María = I see María

Since el número de teléfono is a thing, not a person, there is no personal a.

It is the present simple (also called the present indicative).

From the verb proteger:

• yo protejo
• tú proteges
• él/ella/usted protege
• nosotros protegemos
• vosotros protegéis
• ellos/ellas/ustedes protegen

So in this sentence, protege means protects or sometimes does protect, depending on context.

Spanish word order is more flexible than English, but the normal order here is:

• Subject + verb + object
• El código PIN protege el número de teléfono.

You could change the order for emphasis in some contexts, but this is the most neutral and natural version.

For a learner, this sentence is a good example of standard Spanish word order.