Prima di andare al mercato, controllo la lista della spesa.

After prima di meaning before, Italian normally uses the infinitive when the subject stays the same.

So:

• Prima di andare al mercato, controllo... = Before going to the market, I check...

You cannot say prima di vado because after di you do not use a conjugated verb here.

If the subject changes, Italian usually uses prima che + subjunctive instead:

• Prima che tu vada al mercato... = Before you go to the market...

In your sentence, the same person does both actions, so prima di + infinitive is the natural structure.

Al is a contraction of a + il.

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

So:

• andare al mercato = to go to the market

Italian very often combines a preposition and an article into one word:

• a + il = al
• a + la = alla
• di + la = della
• in + il = nel

This is extremely common and important to recognize.

Italian usually leaves out the subject pronoun when it is clear from the verb ending.

• controllo = I check
• controlli = you check
• controlla = he/she checks

Because the ending -o already shows I, io is not necessary.

You can say io controllo, but it adds emphasis, for example:

• Io controllo la lista, tu prepari le borse. = I check the list, you prepare the bags.

In a neutral sentence, just controllo is more natural.

Here it is a verb, from controllare.

• controllo = I check

Italian also has the noun il controllo, which can mean check, control, or inspection, depending on context.

So compare:

• Controllo la lista. = I check the list.
• Faccio un controllo. = I do a check / inspection.

In your sentence, because it is followed directly by la lista, it is clearly the verb.

Della is di + la, and here la spesa means shopping or more specifically grocery shopping.

So:

• la lista della spesa = literally the list of the shopping
• natural English: the shopping list or the grocery list

This is a very common Italian expression.

Useful related phrase:

• fare la spesa = to do the shopping / grocery shopping

So la spesa often refers to buying food and household items, not just shopping in a general fashion sense.

Italian uses articles more often than English does.

In English, we often drop them:

• go to market is uncommon now, but in some contexts English can be more flexible
• shopping list

In Italian, articles are usually required in expressions like these:

• al mercato
• la lista
• della spesa

So even when English would use fewer articles, Italian often keeps them. This is one of the habits English speakers need to get used to.

Yes. That is completely natural.

Both are correct:

• Prima di andare al mercato, controllo la lista della spesa.
• Controllo la lista della spesa prima di andare al mercato.

The version with prima di andare al mercato at the beginning puts more focus on the time sequence: before going to the market...

The version with the main clause first sounds a bit more straightforward: I check the shopping list before going...

Both are common.

The comma is used because Prima di andare al mercato is an introductory clause before the main clause.

So the sentence is divided like this:

• Prima di andare al mercato, = introductory part
• controllo la lista della spesa. = main statement

In Italian, this comma is very normal and helps readability.

If you put the time phrase at the end, you usually do not need the comma:

• Controllo la lista della spesa prima di andare al mercato.

Not always. Prima can mean different things depending on the structure.

In this sentence:

• prima di = before

But prima can also mean:

• first
• earlier
• beforehand

Examples:

• Prima mangio, poi esco. = First I eat, then I go out.
• Sono arrivato prima. = I arrived earlier.
• Te l’ho detto prima. = I told you before / earlier.

So the exact meaning depends on what comes after it.

Because after prima di, Italian normally uses the infinitive, not the gerund.

Correct:

• prima di andare

Not natural here:

• prima di andando

The form andando is the gerund, used in different structures, such as:

• Sto andando al mercato. = I am going to the market.
• Andando al mercato, ho visto Marco. = While going to the market / On my way to the market, I saw Marco.

So in your sentence, andare is the correct form because it follows prima di.

It can mean market in general, but in everyday contexts like this it often suggests a place where you buy food, produce, and similar items.

So andare al mercato often means going to an open-air market or food market.

That is why it fits very naturally with la lista della spesa. The two parts of the sentence belong well together:

• check the shopping list
• go to the market

In other contexts, mercato can also mean things like the market in an economic sense, but here it is clearly the physical place.