Al mercato compro un’albicocca molto dolce e un avocado maturo per il pranzo.

Because al is the normal contraction of a + il.

• a = to / at
• il = the
• a + il = al

So al mercato means at the market or to the market, depending on context.

This kind of contraction is very common in Italian:

• a + il = al
• a + lo = allo
• a + la = alla
• a + i = ai
• a + gli = agli
• a + le = alle

Al mercato is the natural expression for at the market or to the market in this kind of everyday shopping context.

• Vado al mercato = I go to the market
• Compro frutta al mercato = I buy fruit at the market

Nel mercato literally means in the market, and it is used more when you want to stress being physically inside it, or in other meanings such as the market in an economic sense.

So in this sentence, al mercato is the idiomatic choice.

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

• compro = I buy
• the -o ending tells you it is first person singular

So:

• Io compro = I buy
• Compro = I buy

Both are correct, but compro is more natural unless you want emphasis:

• Io compro, tu cucini = I buy, you cook

Because the feminine singular indefinite article una usually drops its final vowel before a word beginning with a vowel.

So:

• una albicocca becomes un’albicocca

This is called elision.

Examples:

• un’amica
• un’arancia
• un’idea

Notice that this un’ is still feminine, because it comes from una.

Because avocado is masculine, and the masculine indefinite article is un, not una.

For masculine nouns, un normally stays un even before a vowel:

• un avocado
• un amico
• un albero

So:

• un’albicocca = feminine
• un avocado = masculine

The apostrophe here is mainly a clue that the original article was una, not un.

In Italian, descriptive adjectives often come after the noun.

So:

• un’albicocca dolce = a sweet apricot
• un avocado maturo = a ripe avocado

This is the most neutral and common order.

Italian can sometimes put adjectives before the noun, but that often changes the tone or emphasis. For a learner, it is safest to think:

• noun + adjective is very common in Italian

Here, un’albicocca molto dolce sounds natural and standard.

Because here molto is an adverb, not an adjective.

It modifies dolce:

• molto dolce = very sweet

As an adverb, molto does not change for gender or number.

Compare:

• un’albicocca molto dolce = a very sweet apricot
  
  • here molto modifies dolce
• molta frutta = a lot of fruit
  
  • here molta is an adjective and must agree with frutta

So in this sentence, molto stays the same.

Because maturo agrees with avocado, and avocado is masculine singular.

In Italian, adjectives usually agree with the noun they describe in gender and number.

So:

• un avocado maturo = masculine singular
• un’albicocca matura = feminine singular
• due albicocche mature = feminine plural

That is why the sentence has:

• un’albicocca molto dolce
• un avocado maturo

Each adjective matches its own noun.

Because each singular countable noun normally needs its own article.

So Italian says:

• un’albicocca e un avocado

This is the normal way to say an apricot and an avocado.

Italian does not usually let one indefinite article automatically cover both nouns. Repeating the article makes the structure clear and natural.

They mean slightly different things.

• per il pranzo = for lunch, meaning the items are intended for lunch
• a pranzo = at lunch / at lunchtime

In this sentence, the idea is that the speaker is buying the apricot and avocado for the lunch meal, so per il pranzo fits well.

Compare:

• Compro il pane per il pranzo = I buy bread for lunch
• A pranzo mangio un panino = At lunch I eat a sandwich

In modern standard Italian, per + article usually stays separate:

• per il
• per la
• per i
• per gli
• per le

So per il pranzo is the normal modern form.

You may sometimes see older or literary contractions such as pel, but learners should generally use per il.

Yes. Italian word order is fairly flexible.

The original sentence begins with Al mercato to set the scene first:

• Al mercato compro... = At the market, I buy...

If you move it later:

• Compro un’albicocca molto dolce e un avocado maturo al mercato

that is still grammatical. The main difference is emphasis and flow.

Starting with Al mercato highlights the place first, which is very natural in Italian.