Octava puella legit.

Because it describes puella, and puella is a feminine noun.

In Latin, adjectives must agree with the nouns they describe in:

• gender
• number
• case

So:

• puella = feminine, singular, nominative
• octava must also be feminine, singular, nominative

That is why you get octava puella, not octavus puella.

Octava is an ordinal adjective. That means it gives a position in a sequence: first, second, third, eighth, and so on.

So octava means eighth.

It is not the number eight.
If you wanted the cardinal number eight, that would be octo.

So:

• octo puellae = eight girls
• octava puella = the eighth girl

Puella is nominative singular.

You can tell because:

• the ending -a is the normal nominative singular ending for many first-declension nouns
• in this sentence, puella is the subject
• the verb legit is third person singular, so it matches a singular subject

So puella is the one doing the action.

Latin usually does not have a separate word for the or a/an.

So octava puella could mean:

• the eighth girl
• an eighth girl

In practice, context usually makes the sense clear. In many beginner translations, English adds the because it sounds more natural.

Legit is a third person singular verb form.

That means it means:

• he reads
• she reads
• it reads

Since the subject here is puella (girl), the natural English meaning is she reads.

So the structure is:

• octava puella = the eighth girl
• legit = reads

The verb ending itself does not tell you gender.

Latin verbs show:

• person
• number
• often tense, mood, and voice

But they do not normally show whether the subject is male or female.

You know it is she here because the subject is puella, which means girl.

So:

• Marcus legit = Marcus reads / he reads
• Puella legit = the girl reads / she reads

Yes. In ordinary spelling without macrons, legit can be ambiguous.

It can represent:

• legit = reads (present tense)
• lēgit = read (perfect tense)

Macrons show vowel length, and vowel length can change the meaning.

So:

• legit = she reads
• lēgit = she read

If your course has already given the meaning, then that tells you which one is intended.

Yes, Latin word order is much more flexible than English word order.

This sentence could also appear as:

• Puella octava legit
• Legit octava puella
• Octava legit puella

All of these could still mean basically the eighth girl reads, though the emphasis may change.

The endings do most of the grammatical work in Latin, so word order is often used more for style or emphasis than for basic meaning.

Still, adjective + noun + verb is a very natural order, so octava puella legit is perfectly normal.

Because puella is in the nominative case, which is the usual case for the subject of a sentence.

If girl were the direct object, you would expect the accusative form:

• puella = girl as subject
• puellam = girl as direct object

So:

• Puella legit = The girl reads
• Puellam legit would mean something like He/She reads the girl, which is grammatically possible but semantically strange unless the context makes sense

You would usually look them up like this:

• octavus, -a, -um = eighth
• puella, puellae = girl
• lego, legere, legi, lectum = read

A learner may only see octava, puella, and legit in the sentence, but dictionaries usually list the base form or principal parts.

So to identify the words:

• octava comes from octavus
• puella is already the dictionary form
• legit comes from legere / lego

In a basic classroom pronunciation, you could say it roughly as:

• octava = ock-TAH-wah
• puella = poo-EL-lah
• legit = LEH-git or, if it is the perfect lēgit, the first vowel is longer

A more classical-style pronunciation would make:

• v sound like w
• ae sound like ai in some systems, though that does not matter here

So a rough classical pronunciation is: ock-TAH-wa poo-EL-la LEH-git

The structure is:

• octava = adjective describing the subject
• puella = subject noun
• legit = verb

So it is:

[adjective + noun] + verb

More specifically:

The eighth girl reads.

That makes it a very simple Latin sentence: one subject phrase and one verb.