Abans de sortir de la cuina, apago el foc.

In Catalan, abans is normally followed by de when the next verb is in the infinitive.

So the pattern is:

• abans de + infinitive

Examples:

• abans de menjar = before eating
• abans de marxar = before leaving
• abans de sortir = before going out / before leaving

If a full clause follows instead of an infinitive, Catalan usually uses abans que:

• Abans que surtis, apaga el foc. = Before you leave, turn off the stove.

So in your sentence, abans de sortir is the normal and correct structure.

Because sortir de means to go out of or to leave a place.

So:

• sortir de la cuina = to leave the kitchen / to go out of the kitchen

The de shows the place you are coming out of.

Compare:

• sortir de casa = leave the house
• sortir de l’habitació = leave the room
• sortir de la cuina = leave the kitchen

In English, we often just say leave the kitchen, but Catalan commonly uses sortir de in this kind of sentence.

Because la cuina is a specific noun phrase: the kitchen.

Catalan usually uses the definite article with ordinary places like this:

• la cuina = the kitchen
• la casa = the house
• l’escola = the school

So:

• de la cuina = from the kitchen / out of the kitchen

Also, de combines differently depending on the article:

• de + el = del
• de + la = de la
• de + l’ = de l’
• de + els = dels
• de + les = de les

That is why you get de la cuina, not del cuina and not de cuina.

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

• apago already means I turn off
• so jo is not necessary

This is very common in Catalan:

• Parlo català. = I speak Catalan.
• Vaig a casa. = I’m going home.
• Apago el foc. = I turn off the stove / heat.

You can include jo for emphasis or contrast:

• Jo apago el foc, no tu. = I turn off the stove, not you.

But in a neutral sentence, leaving it out is more natural.

Apago is the first person singular present indicative of apagar = to turn off / to put out.

So:

• jo apago = I turn off
• tu apagues = you turn off
• ell/ella apaga = he/she turns off

In this sentence:

• apago el foc = I turn off the stove / burner / heat

This present tense can describe:

• a habitual action: Before leaving the kitchen, I turn off the stove
• a general rule
• or something stated in a vivid, present-style way

Literally, yes: el foc means the fire.

But in kitchen contexts, apagar el foc is a very natural expression meaning something like:

• turn off the stove
• turn off the burner
• turn off the gas
• turn off the heat

So although the literal meaning is I turn off the fire, the natural English translation is often I turn off the stove or I turn off the burner, depending on context.

A few related words:

• el foc = the fire / the heat / the burner
• els fogons = the burners
• la cuina can also mean the kitchen, and in some contexts the stove

Yes. That is also correct.

Both sentences are natural:

• Abans de sortir de la cuina, apago el foc.
• Apago el foc abans de sortir de la cuina.

The difference is mostly one of focus and style:

• Abans de sortir de la cuina, ... puts the time frame first: Before leaving the kitchen...
• Apago el foc abans de sortir de la cuina. starts with the main action: I turn off the stove before leaving the kitchen.

The meaning is essentially the same.

Because the sentence begins with an introductory clause:

• Abans de sortir de la cuina, = Before leaving the kitchen,

Then comes the main clause:

• apago el foc. = I turn off the stove.

Using a comma here is normal and helpful because it separates the introductory part from the main action. It makes the sentence easier to read.

So the structure is:

• introductory clause + comma + main clause

It can be understood as either, and both work well in English.

• sortir often means to go out
• with a place after it, especially sortir de + place, it often means to leave or to go out of

So:

• sortir de la cuina = leave the kitchen / go out of the kitchen

In this sentence, leave the kitchen is probably the most natural English rendering, but go out of the kitchen is also accurate.