In vocabulo “rosa” duae vocales sunt; in vocabulo “flos” plures consonae audiuntur.

Because in takes the ablative when it means in or within in a location sense. Here in vocabulo means in the word.

• vocabulum = nominative singular
• vocabulo = ablative singular

If in took the accusative, it would usually suggest motion into something rather than location.

Vocabulum means word, term, or vocabulary item. It is perfectly good Latin, especially in grammatical or teaching contexts.

A very common Latin word for word is also verbum. So a learner may see either:

• in vocabulo
• in verbo

Both can mean in the word, though verbum is often more common in general Latin.

Because they are being mentioned as words, not used normally inside the sentence.

In English, we do the same thing when we say:

• In the word rose
• In the word flower

The word being discussed is usually left in its citation form. In Latin textbooks this is very common: the author treats rosa and flos as words under discussion, not as nouns playing a grammatical role inside the sentence.

Because duae must agree with vocales in gender.

The numeral two has different forms:

• masculine: duo
• feminine: duae
• neuter: duo

Here vocales is feminine plural, so Latin uses duae.

Originally they are adjectives, but here they are being used as nouns.

So:

• vocalis literally means something like vocal
• consona literally means something like sounding with

But in grammar they commonly mean:

• vocalis = a vowel
• consona = a consonant

In this sentence, vocales and consonae are best understood simply as nouns: vowels and consonants.

They are both nominative plural, because they are the subjects of the verbs.

• duae vocales sunt = two vowels are
• plures consonae audiuntur = more/several consonants are heard

So both noun phrases are doing the job of the subject.

Plures means more or sometimes several, depending on context.

It is the plural comparative form meaning a greater number of. Here it agrees with consonae.

So the sentence is pointing out that in flos there is a larger number of consonants. In a beginner context, this may simply feel like there are several consonants.

Audiuntur means are heard, and it emphasizes sound rather than just spelling.

It is:

• present tense
• passive voice
• 3rd person plural
• from audio

So plures consonae audiuntur literally means more consonants are heard.

A writer could have used sunt instead, but audiuntur makes the statement more about pronunciation and what the ear notices.

Mostly it points toward sounds, especially because of audiuntur.

That said, in elementary Latin grammar, vocales and consonae can refer fairly naturally to vowel and consonant letters too. In these two examples, the number of letters and the number of sounds match closely enough that the sentence works well either way for a beginner.

So:

• rosa has two vowel letters and two vowel sounds
• flos has three consonant letters and three consonant sounds

Flos is one syllable: roughly flohs in a simple English-style approximation.

Its letters are:

• f = consonant
• l = consonant
• o = vowel
• s = consonant

So it has three consonants: f, l, s.

That is why the sentence says plures consonae audiuntur.

The semicolon separates two closely related independent clauses:

• In vocabulo rosa duae vocales sunt
• in vocabulo flos plures consonae audiuntur

A semicolon is stronger than a comma but weaker than a period. It shows that the two statements belong together as a comparison.

Yes. Latin often repeats phrases for clarity in teaching sentences, but it could be made more compact.

For example, after the first clause, a writer might avoid repeating in vocabulo if the context were clear enough. But the full repetition is very natural in a beginner text because it makes the structure easy to see.

So the repetition is mainly pedagogical: it helps the learner notice the pattern.