El passadís on és la carn és a prop de la porta.

Because there are really two clauses inside the sentence:

• on és la carn = where the meat is
• és a prop de la porta = is near the door

So the first és belongs to the relative clause on és la carn, and the second és is the main verb of the whole sentence.

A rough breakdown is:

• El passadís = the aisle
• on és la carn = where the meat is
• és a prop de la porta = is near the door

English does the same thing:

• The aisle where the meat is is near the door.

It looks a little awkward in both languages, but it is grammatically fine.

On means where.

It introduces a relative clause that describes el passadís:

• el passadís on és la carn = the aisle where the meat is

So on links the noun passadís to the place-related information that follows.

Very often, yes, but not always perfectly word-for-word.

In this sentence, on works exactly like where:

• El passadís on és la carn = The aisle where the meat is

Catalan also sometimes uses other structures depending on style or the preposition needed, but for a learner, it is very useful to remember:

• on = where

especially when talking about places.

Catalan uses articles more often than English.

Here, la carn means the meat, but in context it can also feel like the meat section or the place for meat. In a supermarket-style sentence, that is very natural.

So:

• la carn = the meat / the meat section

Using the article helps identify it as a specific thing the speaker and listener can locate.

Passadís literally means corridor or passageway, but in a store context it is often best understood as aisle.

So in this sentence, el passadís is most naturally:

• the aisle

If you were talking about a house or building, passadís would more likely mean hallway or corridor.

A prop de is a fixed expression meaning near or close to.

So:

• a prop de la porta = near the door

You should learn a prop de as one unit.

Examples:

• Som a prop de casa. = We are near home.
• L’escola és a prop del parc. = The school is near the park.

Notice that with a noun after it, Catalan normally uses a prop de + noun.

Because porta is feminine:

• la porta = the door

With de, Catalan does this:

• de + el = del
• de + la = de la

So:

• de + la porta = de la porta
• not del porta

Compare:

• a prop del supermercat = near the supermarket
• a prop de la porta = near the door

Yes, it is normal, although sentences with embedded clauses can feel heavy in both languages.

The structure is:

• El passadís = subject
• on és la carn = relative clause describing the subject
• és a prop de la porta = main predicate

English feels similar:

• The aisle where the meat is is near the door.

Because the subject is long, the sentence can seem awkward. That is normal.

Yes, and many speakers would find that very natural.

• on és la carn = where the meat is
• on hi ha la carn = where there is meat / where the meat section is

In a supermarket context, on hi ha la carn can sound more idiomatic because it focuses on where the meat is found or located.

So both are understandable, but on hi ha la carn may sound more natural in everyday speech.

They mainly show stress, and in some cases they also distinguish words.

• és has an accent and means is
• passadís has the stress on the last syllable: pas-sa-DÍS

In és, the accent also helps distinguish it from es, which is a different word.

For a learner, the important thing is:

• pronounce és clearly as the verb is
• stress passadís on the final syllable

Almost, but the result sounds a bit stiff:

• El = the
• passadís = aisle
• on = where
• és = is
• la carn = the meat
• és = is
• a prop de = near
• la porta = the door

So the literal translation is:

• The aisle where the meat is is near the door.

That is grammatical English, but many English speakers would rephrase it as:

• The meat aisle is near the door.

Catalan often allows the more literal structure quite naturally.