Postea filia codicem fratris capit et duas lineas describit.

Because codicem is the accusative singular form of codex.

In this sentence, filia is the subject, and capit means takes. The thing being taken is the direct object, so Latin puts codex into the accusative:

• nominative: codex = the book / codex as subject
• accusative: codicem = the book / codex as direct object

So filia codicem capit means the daughter takes the book.

Fratris is the genitive singular of frater, meaning of the brother or the brother’s.

So:

• codicem fratris = the brother’s book
• literally: the book of the brother

This is a very common Latin way to show possession.

Because adjectives and numerals in Latin usually agree with the nouns they describe in gender, number, and case.

Here:

• lineas is accusative plural feminine
• so duas must also be accusative plural feminine

That is why Latin uses:

• duas lineas = two lines

If the noun were masculine or neuter, the form of two would be different.

Because lineas is the direct object of describit.

The daughter is describing / copying out something, and the thing she copies is two lines. Direct objects normally go in the accusative.

Also, it is plural because there are two lines:

• singular nominative: linea
• singular accusative: lineam
• plural accusative: lineas

So duas lineas describit means she copies out two lines.

Here describit means something like copies down, copies out, or writes out from another source.

It comes from describere, which can mean:

• to copy
• to write out
• to describe

In this sentence, because she has the brother’s codex and then writes two lines, the sense is clearly copying out rather than just describing in the modern English sense.

Both are present tense, third person singular, active voice.

• capit = she takes
• describit = she copies out / writes out

Third person singular is used because the subject is filia = the daughter, one person.

So the basic structure is:

• filia capit = the daughter takes
• filia describit = the daughter copies out

Because the verb ending already tells you the subject is third person singular.

For example:

• capit = he/she/it takes
• describit = he/she/it copies out

Latin often leaves subject pronouns unstated unless they are needed for emphasis or contrast. Since filia is already named, there is no need to add she.

Latin word order is more flexible than English word order because the endings show the grammatical roles.

So in this sentence:

• filia is the subject because it is nominative
• codicem and duas lineas are objects because they are accusative
• fratris is genitive, showing possession

That means Latin can often rearrange words without changing the basic meaning. However, the chosen order still sounds natural and can give emphasis.

This sentence is fairly straightforward:

• Postea = afterward
• filia = subject
• codicem fratris = object with possession
• capit = first action
• et = and
• duas lineas = second object
• describit = second action

Postea is an adverb meaning afterward, later, or after that.

It tells you when the action happens. It modifies the whole clause, not just one word.

So:

• Postea filia codicem fratris capit...
• Afterward, the daughter takes the brother’s book...

It is very common for Latin adverbs like this to appear near the beginning of the sentence.

Because filia is the subject of both verbs, capit and describit.

The nominative is the case typically used for the subject:

• filia = the daughter as the one doing the action

So the sentence says that the daughter does two things:

1. capit = takes
2. describit = copies out

It joins two actions with the same subject.

The subject filia applies to both verbs:

• filia codicem fratris capit
• (filia) duas lineas describit

Latin often does not repeat the subject if it stays the same. So et here is effectively linking two predicate parts: takes the brother’s book and copies out two lines.

They come from different declensions:

• filia = first declension
• linea = first declension
• frater, fratris = third declension
• codex, codicis = third declension

You can see this in the forms used here:

• filia = nominative singular
• codicem = accusative singular of codex
• fratris = genitive singular of frater
• lineas = accusative plural of linea

This sentence is a good example of how Latin mixes nouns from different declensions in one sentence, while the endings still make each word’s job clear.