Dejo la chaqueta sobre la silla al llegar a casa.

Dejo is the first-person singular present tense of dejar, so it means I leave / I put down.

Spanish often omits the subject pronoun when it is clear from the verb ending. So instead of saying Yo dejo..., Spanish usually just says Dejo...

In this sentence, the person doing the action is therefore I.

Because Spanish is a pro-drop language, which means subject pronouns are often left out when the verb already shows who the subject is.

• dejo = I leave / I put down
• dejas = you leave
• deja = he/she/you formal leaves

Since dejo already clearly means I, adding yo is usually unnecessary unless you want emphasis or contrast:

• Yo dejo la chaqueta, no tú.
  I’m the one who leaves the jacket, not you.

Here, dejar means something like to leave or to put down / set down.

So in this context, it is not about leaving permanently. It is more like:

• putting the jacket somewhere
• leaving it there
• setting it down there

Spanish dejar is very common and can have several meanings depending on context, including:

• to leave
• to let / allow
• to stop / give up in some expressions

In this sentence, the physical meaning of leaving/putting the jacket on the chair is the natural one.

Spanish often uses the definite article (el, la, los, las) with clothing and personal items when it is already obvious whose item it is.

So instead of saying my jacket, Spanish very often says simply the jacket:

• Me quito la chaqueta. = I take off my jacket.
• Dejo la chaqueta sobre la silla. = I leave my jacket on the chair.

Using mi chaqueta is possible, but it sounds more explicit and is only needed if you really want to stress ownership or avoid ambiguity.

Yes, both can be possible, but the nuance is a little different.

• sobre la silla = on the chair, emphasizing that the jacket is on top of the chair
• en la silla = also often translated as on the chair, but can sound a bit more general depending on context

In this sentence, sobre la silla clearly suggests the jacket is placed on the surface or top area of the chair.

A learner should know that Spanish uses prepositions a bit differently from English, and in everyday speech people may choose different ones depending on the exact image they have in mind.

Al llegar means when arriving, upon arriving, or on arriving.

This is a very common Spanish structure:

• al + infinitive

It often expresses when something happens.

Examples:

• Al entrar, saludó a todos. = When he entered, he greeted everyone.
• Al salir, cerré la puerta. = When leaving, I closed the door.

So:

• al llegar a casa = when I arrive home / upon arriving home

Even though English often uses a full clause, Spanish frequently uses this shorter al + infinitive structure.

Formally, yes: al is the contraction of a + el.

However, in al llegar, you should not think of llegar as a noun with an article. It is better to learn al + infinitive as a set pattern meaning when/upon doing something.

So although al is historically and grammatically a + el, in practice here the important thing is the whole structure:

• al llegar
• al entrar
• al salir

These are best understood as time expressions.

Because a casa is a very common expression meaning home.

When Spanish talks about going or arriving home in a general sense, it usually does not use an article:

• Voy a casa. = I’m going home.
• Llego a casa. = I arrive home.

If you say a la casa, it usually sounds more like to the house, meaning a specific building rather than the idea of home.

So:

• llegar a casa = arrive home
• llegar a la casa = arrive at the house

That distinction is very useful.

Yes, most naturally this present tense suggests a habit, routine, or a general action:

• Dejo la chaqueta sobre la silla al llegar a casa. = I leave/put my jacket on the chair when I get home.

Spanish present tense is often used for regular actions, just like English simple present.

Depending on context, it could also describe what someone does in a sequence of actions, but without extra context, the most natural reading is habitual.

Yes, absolutely. That version is very natural too.

Compare:

• Dejo la chaqueta sobre la silla al llegar a casa.
• Cuando llego a casa, dejo la chaqueta sobre la silla.

Both are correct and natural. The difference is mainly stylistic:

• al llegar a casa is a bit more compact
• cuando llego a casa is more explicit and clause-based

Spanish often uses al + infinitive where English learners might expect a full when clause.

Because Spanish word order is flexible, and this placement is very natural.

The sentence first gives the main action:

• Dejo la chaqueta sobre la silla

and then adds the time/context:

• al llegar a casa

This is similar to English:

• I leave my jacket on the chair when I get home.

You could also move the time phrase to the front:

• Al llegar a casa, dejo la chaqueta sobre la silla.

That is also correct. The meaning stays essentially the same.

Either can work, depending on the English style you want.

• I leave my jacket on the chair when I get home
• I put my jacket on the chair when I get home

If you want to stay closer to dejar, leave is a good match.
If you want more natural everyday English in some contexts, put may sound better.

That is common in translation: one Spanish verb may correspond to more than one English verb depending on context.

The sentence itself is standard Spanish and would be understood everywhere in the Spanish-speaking world.

Nothing in it is strongly limited to Spain. However, since the learner is studying Spanish from Spain, it is still perfectly good Spanish for that variety.

The only small point worth noting is that preposition choices like sobre versus en can vary a little by speaker and region, but the sentence is fully natural and standard.