In pescheria la pescivendola pulisce il tonno e mi spiega come cucinarlo.

In pescheria is a very common Italian way to mean at the fish shop / at the fishmonger’s in a general sense.

Italian often uses in + place noun without an article when talking about the kind of place where something happens:

• in banca = at the bank
• in farmacia = at the pharmacy
• in chiesa = in church
• in pescheria = at the fish shop

If you say nella pescheria, that usually sounds more specific: in the fish shop, meaning a particular one already known from the context.

So here In pescheria means something like At the fish shop in a general scene-setting way.

They are two different words:

• pescheria = the fish shop / fish market stall
• pescivendola = the female fish seller / fishmonger

So in the sentence:

• In pescheria = at the fish shop
• la pescivendola = the fishmonger

A related masculine form is:

• pescivendolo = male fish seller

Yes, the article is normally used in Italian before a noun like this.

• la pescivendola = the fishmonger

Italian uses definite articles much more often than English. Where English may say the fishmonger or sometimes just a fishmonger depending on style, Italian usually wants the article.

Here la agrees with pescivendola, which is a feminine singular noun.

Both are in the present indicative:

• pulisce = she cleans
• spiega = she explains

In Italian, the present tense is often used just like the English present, but it can also sound natural in contexts where English might use the present continuous:

• la pescivendola pulisce il tonno
  = the fishmonger cleans / is cleaning the tuna

So depending on context, English may translate it as either simple present or present continuous.

Italian often uses the definite article where English may or may not use one.

• il tonno = the tuna

Here it refers to the specific tuna being prepared, so il is natural.

Italian generally likes articles with direct objects more than English does. Saying just tonno here would sound incomplete or would change the structure.

Mi means to me here.

• spiega = explains
• mi spiega = explains to me

This is an indirect object pronoun. Italian uses these short pronouns before the verb:

• mi = to me
• ti = to you
• gli / le = to him / to her
• ci = to us
• vi = to you all
• gli = to them

So:

• mi spiega come cucinarlo
  = she explains to me how to cook it

Come cucinarlo is a very standard Italian structure:

• come = how
• cucinare = to cook
• -lo = it

So cucinarlo literally means to cook it.

When an object pronoun is attached to an infinitive, it goes on the end:

• cucinare + lo = cucinarlo
• mangiare + la = mangiarla
• comprare + li = comprarli

You could also say come cucinare il tonno, and that would mean how to cook the tuna. But once il tonno has already been mentioned, Italian often prefers the pronoun:

• il tonno ... come cucinarlo
  = the tuna ... how to cook it

Come lo cucinare is not correct. If you use a conjugated verb, you would need something like:

• come lo cucino = how I cook it
• come lo cucinare is ungrammatical

-Lo refers back to il tonno.

• il tonno is masculine singular
• so the direct object pronoun is lo

That is why we get:

• cucinarlo = to cook it / to cook the tuna

If the noun were feminine singular, it would change:

• la sogliola → cucinarla

If it were masculine plural:

• i gamberi → cucinarli

In Italian, object pronouns are often attached to infinitives, gerunds, and affirmative commands.

So:

• cucinare + lo → cucinarlo
• mangiare + la → mangiarla
• prendere + li → prenderli

This is very normal after words like come, per, prima di, and after many verbs where an infinitive follows.

In this sentence, come cucinarlo means how to cook it, so attaching the pronoun to the infinitive is exactly what you would expect.

Grammatically, yes, but it would sound different.

• mi spiega = neutral, normal way to say explains to me
• spiega a me = more emphatic, like explains to me specifically

Italian usually prefers the pronoun form unless there is contrast or emphasis.

For example:

• Mi spiega come cucinarlo. = She explains to me how to cook it.
• Spiega a me, non a te. = She explains to me, not to you.

So in your sentence, mi spiega is the natural choice.

Yes, Italian word order is flexible, but this is the most neutral order:

• subject: la pescivendola
• verb: pulisce
• object: il tonno
• verb + pronoun: mi spiega
• complement: come cucinarlo

This is the basic, natural order for a simple statement.

Italian can move things around for emphasis, for example:

• Il tonno la pescivendola lo pulisce e mi spiega come cucinarlo.

But that is more marked and less neutral. For learners, the original order is the best model.

It is an infinitive construction, not a full finite clause.

• come cucinarlo = how to cook it

English does the same thing:

• She explains how to cook it.

There is no expressed subject in to cook it, and that is normal. Italian works the same way with the infinitive:

• come farlo = how to do it
• come prepararla = how to prepare it
• come cucinarlo = how to cook it

In this sentence, il tonno most naturally means a specific tuna or a specific piece of tuna that the fishmonger is cleaning.

Because of the article il and the context, it is not just tuna as a general food category. It is the tuna being handled right there.

So the sentence gives a concrete scene:

• at the fish shop,
• the fishmonger cleans the tuna,
• and explains to me how to cook it.

You would change la pescivendola to il pescivendolo:

• In pescheria il pescivendolo pulisce il tonno e mi spiega come cucinarlo.

The rest of the sentence stays the same because:

• il tonno is still masculine singular
• mi still means to me
• cucinarlo still refers to il tonno

The dictionary form is pulire = to clean.

Pulire is a third-conjugation -ire verb, and many -ire verbs insert -isc- in some forms of the present tense.

For pulire:

• io pulisco = I clean
• tu pulisci = you clean
• lui/lei pulisce = he/she cleans
• noi puliamo = we clean
• voi pulite = you all clean
• loro puliscono = they clean

So pulisce is the normal she cleans form of pulire.

No. Here come means how, not like.

Italian come can mean different things depending on context:

• come? = how?
• come te = like you
• mi spiega come cucinarlo = she explains how to cook it

In this sentence, after spiega, it clearly means how.