Mater ad macellum aliquot mala et pira emptum it.

Because ad takes the accusative when it means to or toward a place.

• ad macellum = to the market
• macellum is a neuter second-declension noun
• its nominative is macellum
• its accusative singular is also macellum

So even though the form looks unchanged, it is accusative because of ad.

Macellum means a market, especially a provision market or meat/food market. It is not just any open space; it is specifically a place where food is bought and sold.

So ad macellum it means she goes to the market.

Because this is the supine in -um, used after a verb of motion to express purpose.

• it = goes
• emptum = to buy

So emptum it literally means she goes for buying, or more naturally, she goes to buy.

This is a standard Latin construction:

• venit visum = he came to see
• legatos missit rogatum auxilium = he sends ambassadors to ask for help

So in your sentence, emptum is completely normal Latin after it.

It comes from the verb emo, emere, emi, emptum, meaning buy.

So the principal parts are:

• emo = I buy
• emere = to buy
• emi = I bought
• emptum = bought / the supine form used here

In this sentence, emptum is the supine form used with it.

They are the direct objects of the implied action buying, so they are in the accusative plural.

• malum = apple
• pirum = pear

Both are neuter nouns, and for neuter nouns:

• nominative plural ends in -a
• accusative plural also ends in -a

So:

• mala can be nominative plural or accusative plural
• pira can be nominative plural or accusative plural

Here they are accusative plural because they are the things being bought.

Yes. Here mala is from malum, meaning apple.

That is different from:

• malus, mala, malum = bad

So Latin has two different words that can look similar:

• malum (noun) = apple
• malum (adjective/neuter form) = bad thing or evil, depending on context

In this sentence, because it is paired with pira and occurs in a shopping context, mala clearly means apples.

Aliquot means some or several.

It is indeclinable, which means its form does not change for gender, number, or case.

So Latin says:

• aliquot mala = some apples
• aliquot pira = some pears

Even though mala and pira are plural accusatives, aliquot stays exactly the same.

Grammatically, it most naturally goes with the whole phrase mala et pira.

So the sense is:

• some apples and pears or
• some apples and some pears

Latin often places one modifier before the first noun and lets it cover the coordinated phrase.

Latin has no word for the or a/an.

So mater can mean:

• mother
• the mother
• a mother

The exact sense comes from context.

It is in the nominative singular because it is the subject of it.

No. Here it is a Latin verb, from eo, ire, meaning go.

• it = he/she/it goes

Since the subject is mater, it means she goes.

It is only a coincidence that the Latin word looks like the English pronoun it.

Yes, that would also be possible, but it is a different construction.

• emptum it uses the supine after a verb of motion
• ut ... emat uses a purpose clause

Both can mean she goes to the market to buy apples and pears.

The supine construction is often shorter and very common with verbs of motion when the purpose is straightforward.

Latin word order is more flexible than English word order.

This sentence is arranged quite naturally:

• Mater = subject first
• ad macellum = where she goes
• aliquot mala et pira = what she is going to buy
• emptum = purpose
• it = verb at the end

Ending with the verb is very common in Latin. Also, putting emptum near it makes the purpose construction clear.

Because Latin often places related words where they fit the rhythm or emphasis of the sentence, not always where English would.

Even though mala et pira are logically the objects of buying, Latin can state them before the supine emptum. The meaning is still clear:

• Mater ad macellum aliquot mala et pira emptum it
• Mother goes to the market to buy some apples and pears

Latin readers understand that the apples and pears are what she is going to buy.