El forn encara és brut perquè ahir hi vam fregir verdures i ara fa mala olor.

Because Catalan normally uses the definite article with a specific, known thing: el forn = the oven.

Here, the speaker is talking about a particular oven, not ovens in general.
So:

• El forn = the oven
• Un forn = an oven
• Forn by itself would not sound natural here

Catalan uses articles very regularly, often in places where English learners may be tempted to leave them out.

Here encara means still.

So:

• El forn encara és brut = The oven is still dirty

It shows that the dirty state has continued up to the present moment.

A useful contrast:

• encara = still / yet
• ara = now

Both appear in this sentence, but they do different jobs.

Because they express different ideas:

• encara = the situation continues
• ara = at this moment / now

So the sentence is structured like this:

• El forn encara és brut = The oven is still dirty
• i ara fa mala olor = and now it smells bad

In other words, encara describes continuation, while ara points to the present time.

This is a very common question for English speakers, especially if they also know Spanish.

In Catalan, ser is often used more broadly than Spanish ser, and you can hear és brut in contexts where English would simply say is dirty.

That said, many speakers also say està brut when they want to emphasize the oven’s current temporary condition. So in modern Catalan, both can be heard, depending on speaker, region, and style.

A simple learner-friendly way to think about it:

• és brut = describes the oven as dirty
• està brut = often stresses its present state

So the sentence is natural, even if està brut may also sound very natural to many speakers.

Here perquè means because.

So:

• perquè ahir hi vam fregir verdures = because yesterday we fried vegetables in it

The accent matters because Catalan distinguishes several similar-looking forms:

• perquè = because
• per què = why / for what reason
• per a què = what for / for what purpose

So in this sentence, the accented one-word form perquè is correct because it introduces the reason.

Hi is a very important Catalan pronoun. Here it refers to a place: in it / there.

In this sentence, hi refers back to el forn. So:

• ahir hi vam fregir verdures literally means something like
  yesterday we fried vegetables there / in it

It replaces a location phrase such as:

• al forn
• dins del forn

Catalan uses hi very often where English would simply say there, in it, or sometimes nothing explicit at all.

Because unstressed pronouns like hi normally go before a conjugated verb, and in compound forms they go before the auxiliary part.

So:

• hi vam fregir

not:

• vam hi fregir ✘

Since vam fregir is the periphrastic past, the pronoun comes before vam.

This is a standard Catalan pronoun position pattern:

• hi vaig anar
• ho vam veure
• li van dir

Vam fregir is the periphrastic past, one of the normal ways to talk about a completed past action in Catalan.

It is formed with:

• vaig, vas, va, vam, vau, van
  • infinitive

So:

• vam fregir = we fried

In this sentence, it fits well because the action happened at a specific finished time:

• ahir = yesterday

The subject is we, which is why the form is vam.

Because Catalan often leaves subject pronouns out when the verb already makes the subject clear.

• vam already tells you the subject is nosaltres = we

So:

• (nosaltres) vam fregir verdures

Both are possible, but normally Catalan omits nosaltres unless it is needed for emphasis or contrast.

This is very common in Catalan:

• Parlo = I speak
• Parles = you speak
• Parlem = we speak

Because here verdures is being used in a general, non-specific way: vegetables.

So:

• vam fregir verdures = we fried vegetables

If you said les verdures, it would usually mean specific vegetables already known in the conversation:

• vam fregir les verdures = we fried the vegetables

If you said unes verdures, it would mean some vegetables, but that is less neutral here.

So the version in the sentence sounds natural and general.

Because fer olor is the normal Catalan expression for to smell in the sense of to give off a smell.

So:

• fa mala olor = it smells bad / it gives off a bad smell

This is a very common structure:

• fa bona olor = it smells good
• fa olor de fum = it smells of smoke
• fa pudor = it stinks

English uses smell as a verb very naturally, but Catalan often uses fer olor.

Because mala olor is the normal fixed expression.

In Catalan, adjectives often come after the noun, but some very common adjectives, especially in set expressions, can come before it. Mala olor is one of those standard combinations.

So learners should treat it almost as a chunk:

• bona olor = good smell
• mala olor = bad smell

That is much more natural than olor mala here.

Some parts are flexible, but the given order is very natural.

For example, these are possible:

• El forn encara és brut perquè ahir hi vam fregir verdures i ara fa mala olor.
• Ahir hi vam fregir verdures, per això el forn encara és brut i ara fa mala olor.

But some things should stay in place:

• hi should stay before vam
• encara should stay near what it modifies
• perquè introduces the reason clause

So the sentence is not completely fixed, but its current order is clear and idiomatic.