Epistulam a matre scriptam puella iterum legit.

Because epistulam is accusative singular. In this sentence, it is the direct object of legit.

The basic noun is epistula = letter.
Its forms include:

• epistula = nominative singular
• epistulam = accusative singular

Latin uses endings to show a word’s job in the sentence. So epistulam means that the letter is the thing being read.

Because puella is in the nominative case, which is the case normally used for the subject.

A native English speaker often expects the subject to come first, but Latin does not depend mainly on word order. It depends much more on case endings.

So in:

Epistulam ... puella ... legit

you identify puella as the subject not by position, but by its form:

• puella = nominative singular = the girl
• epistulam = accusative singular = the letter

That tells you that the girl is doing the reading.

Scriptam is a perfect passive participle of scribo (write). Here it means written.

It ends in -am because it agrees with epistulam. In Latin, adjectives and participles must agree with the noun they describe in:

• gender
• number
• case

So:

• epistulam = feminine, singular, accusative
• scriptam = feminine, singular, accusative

That agreement shows that scriptam describes epistulam:
the letter written...

Latin very often uses a participle phrase where English might prefer a relative clause.

So instead of saying something like:

• the letter which was written by the mother

Latin can compress that idea into:

• epistulam a matre scriptam

Literally: the letter written by the mother

This is very normal Latin style. It is compact and elegant.

Because after a/ab meaning by with a passive idea, Latin uses the ablative case to show the personal agent.

Here, the writing is understood passively in scriptam = written, so the person who did the writing is expressed as:

• a matre = by the mother

The noun mater has the ablative singular form matre.

So:

• mater = mother
• matre = by/from/with the mother, depending on context
• here specifically: by the mother

Both a and ab mean the same thing here: by.

Latin usually prefers:

• ab before vowels and often before certain consonants
• a before most consonants

Since matre begins with m, a matre is the normal form.

So this is just a regular phonetic choice, not a difference in meaning.

Because of agreement.

Compare the forms:

• epistulam = feminine singular accusative
• scriptam = feminine singular accusative
• puella = feminine singular nominative

Since scriptam is accusative, it matches epistulam, not puella.

If it described puella, you would expect scripta, not scriptam.

So the grammar makes the connection clear even if the words are separated.

Iterum means again. As an adverb, it modifies the verb legit.

Latin adverbs often have flexible placement. Here it sits just before the verb:

• puella iterum legit = the girl reads/read the letter again

That position is very natural, but Latin could move iterum elsewhere for emphasis without changing the core meaning.

So yes, position can affect emphasis, but not necessarily the basic sense.

This is a very common question, because without macrons the form is ambiguous in writing.

• legit can be present: he/she reads
• lēgit can be perfect: he/she read

When macrons are not written, both appear as legit.

So you usually decide from:

• the context
• the given translation
• sometimes the style of the passage

In this sentence, you rely on the meaning already provided to know whether it is reads or read.

Classical Latin normally has no articles like English the and a/an.

So:

• epistulam can mean a letter or the letter
• puella can mean a girl or the girl
• matre can mean a mother, the mother, or simply mother, depending on context

English must choose an article, but Latin usually leaves that to context.

Yes, very often.

Because Latin uses endings to show grammatical function, the sentence could be rearranged in several ways without changing the basic meaning. For example, all of these could express the same core idea:

• Puella epistulam a matre scriptam iterum legit.
• Puella iterum epistulam a matre scriptam legit.
• A matre scriptam epistulam puella iterum legit.

What changes most is the focus or emphasis, not the underlying grammar.

That is one of the biggest differences between Latin and English: Latin word order is much freer.

Yes. It is best understood as a phrase describing epistulam.

You can mentally group it like this:

• epistulam [a matre scriptam]

That whole bracketed phrase tells you which letter:

• the letter written by the mother

This is helpful when reading Latin: look for nouns and then see what adjectives, participles, or prepositional phrases belong with them.

A good step-by-step approach is:

1. Find the main verb: legit
2. Find the nominative subject: puella
3. Find the accusative object: epistulam
4. Notice what modifies the object: scriptam
5. Notice the agent of the passive participle: a matre
6. Notice the adverb: iterum

So the structure is roughly:

• puella = subject
• legit = verb
• epistulam = object
• a matre scriptam = description of the object
• iterum = adverb modifying the verb

That is a very useful reading strategy for Latin in general.