Mater dicit se a bibliopola iterum vocari, quia ille aliud volumen Graecum monstrare velit.

Because se is the reflexive pronoun, and it refers back to the subject of the main verb, Mater.

After a verb of saying, thinking, knowing, and so on, Latin often uses an accusative + infinitive construction for indirect statement:

Mater dicit se vocari
literally: Mother says herself to be called

In smoother English, we say Mother says that she is being called.

If Latin used eam, that would normally mean her as someone other than the subject Mater.

Because after dicit, Latin usually puts the reported statement into an infinitive clause, not a finite clause introduced by that.

So:

• dicit = she says
• se = the accusative subject of the infinitive
• vocari = to be called

This is the standard Latin way to express indirect statement.

Also, vocari is present passive infinitive, so it shows an action happening at the same time as dicit: she says that she is being called.

Because some Latin nouns ending in -a are still masculine, especially words borrowed from Greek or words for male professions.

bibliopola means bookseller and is one of those masculine first-declension nouns.

So even though it looks like a typical first-declension feminine noun, it is masculine in meaning.

It gives the personal agent with a passive verb.

With a passive verb, Latin often uses:

a/ab + ablative = by

So:

• vocari = to be called
• a bibliopola = by the bookseller

Since bibliopola is the person doing the action, it appears in the ablative after a.

iterum is an adverb meaning again, and it modifies vocari.

So the sense is that she is being called again.

Latin adverbs are fairly flexible in position, so iterum could appear in different places without changing the basic meaning. Here it sits neatly next to the infinitive phrase.

It refers to bibliopola, the bookseller.

Latin often uses ille not just for that, but also as a stronger he, especially when the speaker wants to point back clearly to someone already mentioned.

So here ille means something like:

• he
• or a slightly more pointed that man

Yes, Latin could have left it out, because the ending of velit already tells you the subject is third-person singular.

But ille is useful for clarity or emphasis. It makes it especially clear that the one who wants to show the book is the bookseller, not the mother.

So the pronoun is not required, but it helps point to the right person.

This is a very common question.

velit is the present subjunctive of velle. After quia, Latin often uses the indicative for a straightforward factual reason, but the subjunctive can be used when the reason is presented as subjective, reported, or viewed from someone’s perspective rather than simply stated by the narrator as fact.

Here the idea is roughly: this is the reason as the mother gives or understands it.

So:

• quia ille ... vult would sound more like an objective statement of fact
• quia ille ... velit gives a more reported or subjective coloring

At an early stage, it is enough to notice that the clause gives the supposed or reported reason.

It is the object of monstrare.

More specifically:

• aliud = another, neuter singular accusative
• volumen = volume/book/scroll, neuter singular accusative
• Graecum = Greek, neuter singular accusative

All three words agree and belong together.

So the phrase means another Greek book/volume.

Because it depends on velit.

After velle in Latin, you normally use an infinitive to say what someone wants to do:

• vult venire = he wants to come
• velit monstrare = he wants to show

So monstrare is a complementary infinitive completing the meaning of velit.

Not especially. Latin word order is much freer than English word order because case endings show each word’s function.

This sentence is arranged in a natural Latin way:

• Mater dicit starts with the main statement
• se a bibliopola iterum vocari gives the indirect statement
• quia ille aliud volumen Graecum monstrare velit gives the reason

A few points of style:

• aliud comes before volumen to highlight another
• Graecum comes after volumen, which is a very common position for an adjective
• iterum sits close to vocari, the action it modifies

So the order is flexible, but the sentence as written is perfectly normal Latin.