Il lucchetto si apre con la combinazione.

Lucchetto means padlock — the lock itself, usually a portable one you attach to something.

It is not the same as serratura.

• lucchetto = padlock
• serratura = lock mechanism, especially the one built into a door

So in Il lucchetto si apre con la combinazione, the subject is specifically the padlock.

Italian often uses the definite article where English may or may not use one.

• il = the
• lucchetto = padlock

So il lucchetto literally means the padlock.

In Italian, using the article here sounds natural because you are talking about a specific object or about the padlock as the thing being described. English sometimes drops articles in more general statements, but Italian usually keeps them.

This is one of the most common questions, because si can be tricky.

Here, si apre means something like:

• opens
• can be opened
• opens itself in form, though not always literally in meaning

The verb is aprire = to open.

• apre = opens
• si apre = a reflexive or si-passivante / impersonal-passive-like form, often used when something opens rather than someone explicitly opens it

So:

• Il lucchetto apre would sound wrong here.
• Il lucchetto si apre is the natural way to say The padlock opens / can be opened.

It focuses on the padlock and the way it opens, not on the person doing the action.

Grammatically, it looks reflexive, but in this kind of sentence it is usually best understood as intransitive or as a common Italian way to express that something opens.

So although si apre can look like opens itself, the most natural English understanding is simply:

• opens
• is opened
• can be opened

With objects like doors, windows, locks, and shops, Italian very often uses this structure:

• La porta si apre facilmente = The door opens easily
• Il negozio si apre alle nove = The shop opens at nine

So in your sentence, don’t over-translate si as itself.

Con usually means with.

So:

• con = with
• la combinazione = the combination

Together, con la combinazione means with the combination.

In natural English, that often becomes:

• using the combination
• by entering the combination

So the phrase tells you how the padlock opens.

Yes. Combinazione is a feminine noun, so it takes:

• la combinazione = the combination

That is why the article is la, not il.

A helpful pattern: many Italian nouns ending in -zione are feminine:

• la stazione
• la lezione
• la situazione
• la combinazione

Yes, in this context combinazione means the combination of a combination lock — the sequence of numbers or symbols needed to open it.

A learner might wonder whether codice could also work. Sometimes it can, depending on context, but there is a nuance:

• combinazione = combination, especially for a lock
• codice = code, password, code number, access code

For a padlock with turning numbers, combinazione is very natural.

Sometimes yes, but it changes the nuance.

• con la combinazione suggests a classic combination lock
• con il codice suggests a code, possibly digital or electronic

So if it is a traditional padlock with a number combination, con la combinazione is the better choice.

The word order is:

• Il lucchetto = subject
• si apre = verb
• con la combinazione = prepositional phrase explaining means

So the structure is:

Subject + verb + how/with what

This is a very normal Italian sentence order.

Yes, a few alternatives are possible, depending on style and emphasis.

For example:

• Il lucchetto si apre usando la combinazione = The padlock opens using the combination
• Il lucchetto si apre inserendo la combinazione = The padlock opens by entering the combination
• Il lucchetto si apre tramite combinazione = The padlock opens by means of a combination

But Il lucchetto si apre con la combinazione is simple, natural, and idiomatic.

Then you would usually use a more active structure.

For example:

• Si apre il lucchetto con la combinazione is possible in some contexts, but less direct for a beginner.
• Apri il lucchetto con la combinazione = You open the padlock with the combination
• Il lucchetto si può aprire con la combinazione = The padlock can be opened with the combination
• Si apre il lucchetto usando la combinazione = The padlock is opened using the combination

Your original sentence avoids mentioning the person and keeps the focus on the object.

It is pronounced approximately look-KET-toh.

A few pronunciation notes:

• lu sounds like loo
• cche gives a hard k sound, not a ch sound
• the stress is on -chet-

So:

lucchetto → look-KET-toh

This happens because che and chi in Italian have a hard k sound:

• che = keh
• chi = kee

It could be either, depending on context.

It can mean:

• a general fact: The padlock opens with the combination
• an instruction-like statement: The padlock is opened with the combination
• a description of how the mechanism works

Italian often uses the present tense this way, just like English.

So without more context, the sentence is flexible and natural in several situations.