Pela les pastanagues i posa-les a la safata abans d'encendre el forn.

Pela is the tu imperative form of pelar (to peel).

• pelar = infinitive, to peel
• tu peles = present tense, you peel
• pela! = command to one person you address as tu, peel!

So Pela les pastanagues means Peel the carrots as an instruction to one person.

In Catalan, with affirmative commands, object pronouns are usually attached to the end of the verb.

So:

• posa = put
• les = them (feminine plural)
• posa-les = put them

The hyphen is standard in this structure.

Les is a direct object pronoun meaning them, referring back to les pastanagues.

Because pastanagues is:

• feminine
• plural

the pronoun must also be feminine plural: les

So the sentence first says the carrots, and then later uses them to avoid repeating the noun.

Catalan often uses the definite article more widely than English does.

So les pastanagues literally means the carrots. In a recipe or instruction context, Catalan commonly uses the article where English may also use the, but sometimes Catalan sounds more natural with articles in places where English might omit them.

Here, les pastanagues is simply the normal way to say the carrots.

This is just natural style.

Catalan, like English, often avoids repetition:

• Pela les pastanagues i posa les pastanagues a la safata = grammatical but repetitive
• Pela les pastanagues i posa-les a la safata = more natural

It works just like English Peel the carrots and put them on the tray.

A here means something like onto / in / on, depending on context. With posar, Catalan often uses a before the place where something is put.

So:

• posar alguna cosa a la safata = to put something on/into the tray

Even if English might choose on the tray, Catalan naturally uses a here.

Because de contracts to d' before a vowel or silent h.

• abans de + encendre
• becomes abans d'encendre

This is very common in Catalan:

• abans d'arribar
• després d'estudiar
• d'obrir

After abans de (before), Catalan normally uses an infinitive when the subject is general or understood from context.

So:

• abans d'encendre el forn = before turning on the oven

This is similar to English before turning on the oven.

Encendre means to turn on, to light, or to switch on, depending on the thing involved.

So:

• encendre el forn = to turn on the oven

It is the normal verb for activating something like an oven, a light, or a fire.

It is talking to one person, informally, because the commands are:

• pela
• posa

These are tu imperative forms.

If it were addressed to more than one person (vosaltres), it would be:

• Peleu les pastanagues i poseu-les a la safata...

Yes. If you were addressing one person formally (vostè), the commands would be different:

• Peli les pastanagues i posi-les a la safata abans d'encendre el forn.

So the original sentence is clearly informal tu language.

Because the noun is introduced first, and then the pronoun refers back to it.

Structure:

• Pela les pastanagues = first mention the object clearly
• i posa-les a la safata = then refer back to it with les

This is very natural and works like English:

• Peel the carrots and put them on the tray.

Usually safata means tray. In cooking, it can also refer to a baking tray or oven tray, depending on context.

So in this sentence, a la safata most likely means something like:

• onto the tray
• onto the baking tray

The exact English choice depends on the context of the recipe or instruction.