Mater duas lactucas et unam betam a mercatrice emit.

Because mater is in the nominative singular, the case normally used for the subject.

So in this sentence:

• mater = the one doing the action
• emit = the action

Latin does not rely on word order as much as English does. Even if the words were rearranged, mater would still be the subject because of its case.

They are in the accusative case because they are the direct objects of emit: they are the things being bought.

• lactucas = accusative plural
• betam = accusative singular

So Latin marks what is being bought with the accusative.

Because Latin numbers used as adjectives must agree with the nouns they describe in gender, number, and case.

Both lactuca and beta are feminine, so their numbers must also be feminine:

• duas lactucas = two lettuces
  
  • duas is feminine accusative plural
• unam betam = one beet
  
  • unam is feminine accusative singular

So the forms change to match the nouns.

Yes, Latin could often just say betam if the idea of a beet or one beet is clear from context.

Using unam makes the number explicit: one beet.

This is especially worth noticing because Latin has no word for a/an. So:

• betam can mean a beet or the beet, depending on context
• unam betam specifically means one beet

Mercatrice is in the ablative singular.

It is ablative because it follows the preposition a, which here means from:

• a mercatrice = from the merchant / from the female seller

So this phrase shows the source of the purchase.

Also, the dictionary form is mercatrix, so:

• nominative: mercatrix
• ablative: mercatrice

In classical usage, a is commonly used before a consonant, and ab before a vowel or h.

Since mercatrice begins with m, a mercatrice is the expected form.

So:

• a mercatrice = normal before a consonant
• ab amica = normal before a vowel

You may still sometimes see variation in Latin texts, but this is the usual rule learners are taught.

It comes from emo, emere, meaning to buy.

But there is an important detail: without macrons, emit can be ambiguous.

• emit = buys (present)
• ēmit = bought (perfect)

Since many Latin texts omit macrons, the written form emit could represent either one. Usually the intended meaning is clear from context or from the translation already given to the learner.

The word order is normal and natural, but it is not fixed the way English word order is.

This sentence has:

• subject first: Mater
• objects next: duas lactucas et unam betam
• prepositional phrase: a mercatrice
• verb last: emit

Putting the verb at or near the end is very common in Latin, but not required. Latin can move words around more freely because the endings show their roles.

For example, the meaning would stay basically the same in a different order, such as:

• Mater a mercatrice duas lactucas et unam betam emit.

The exact emphasis might shift, but the grammar still works.

Because Latin has no articles.

English uses articles constantly:

• the mother
• a merchant
• the beet

Latin does not have separate words for the or a/an. Instead, readers understand that from context.

So:

• mater can mean mother, the mother, or sometimes a mother
• mercatrice can mean from a merchant or from the merchant, depending on context

Yes. Mercatrix is a feminine noun, meaning a female merchant, female seller, or female trader.

Its masculine counterpart is mercator.

So:

• a mercatrice = from a female merchant
• a mercatore = from a male merchant

Latin often marks this distinction more clearly than English does.

That is a good language difference to notice.

In Latin, lactuca can be treated as a countable noun, so duas lactucas means something like two lettuces, that is, two heads/bunches of lettuce.

English often uses lettuce as a mass noun, but it can also say two lettuces in certain contexts, especially when talking about whole heads in a market.

So the Latin is perfectly normal; it is just using a vegetable as something countable.

A learner often wants to know what forms to look up. The dictionary forms are:

• mater = mater, matris = mother
• lactucas from lactuca, lactucae = lettuce
• betam from beta, betae = beet
• mercatrice from mercatrix, mercatricis = female merchant
• emit from emo, emere, emi, emptum = buy

Knowing the dictionary form helps you identify the declension or conjugation and understand why the word looks the way it does in the sentence.