Avunculus dicit nepotem et neptem tam prudentes esse quam parentes eorum.

The sentence has two parts:

• Avunculus dicit = The uncle says
• nepotem et neptem tam prudentes esse quam parentes eorum = the thing he says

That second part is an indirect statement. After verbs like dicit (says), Latin often uses:

• an accusative for the subject of the reported statement
• an infinitive for the verb

So Latin literally does something like:

• The uncle says the nephew and niece to be as wise as their parents.

Natural English uses that instead:

• The uncle says that the nephew and niece are as wise as their parents.

Because they are the subject of an infinitive in an indirect statement.

After dicit, Latin does not normally say:

• nepos et neptis sunt ...

Instead, it changes the subject into the accusative:

• nepotem et neptem

So:

• nepos becomes nepotem
• neptis becomes neptem

If you turned the reported statement into a direct statement, the subject would go back to the nominative:

• nepos et neptis ... sunt

Esse is the infinitive of sum, meaning to be.

Since Latin uses an infinitive in indirect statement, English are becomes Latin esse:

• direct-style idea: are wise
• indirect-statement form: to be wise = prudentes esse

So dicit nepotem et neptem prudentes esse means:

• he says that the nephew and niece are wise

Because it describes two people:

• nepotem = nephew/grandson
• neptem = niece/granddaughter

Since there are two of them together, the adjective must be plural.

Also, because it belongs to the accusative subject of the infinitive, it is in the accusative plural:

• prudentes

Its dictionary form is prudens, prudentis.

Because the accusative plural form of prudens is the same for masculine and feminine:

• masculine accusative plural: prudentes
• feminine accusative plural: prudentes

Since nepotem is masculine and neptem is feminine, Latin can still use one shared plural adjective:

• prudentes

Tam ... quam means as ... as.

So here:

• tam prudentes quam parentes eorum

means:

• as wise as their parents

This is a very common comparison pattern in Latin:

• tam + adjective/adverb + quam

Examples:

• tam fortis quam frater = as brave as his brother
• tam celeriter quam potest = as quickly as he can

Here parentes is accusative plural.

In a comparison with quam, the compared word often stands in the same case as the word it is being compared with. The nephew and niece are the understood subject of esse in the accusative, so parentes also appears in the accusative plural.

A helpful detail: with parentes, the nominative plural and accusative plural look the same:

• nominative plural: parentes
• accusative plural: parentes

So the form does not change visibly, even though the grammatical role matters.

Eorum is the genitive plural of is, ea, id, and it means of them or their.

So:

• parentes eorum = their parents

Latin often expresses third-person possession this way.

A learner may wonder about suus. That is the reflexive possessive, and in reported speech it can become harder to interpret clearly. Eorum is a straightforward way to show that the parents belong to them.

Because Latin often leaves out a repeated verb when it is easy to understand.

The full idea is something like:

• the nephew and niece to be as wise as their parents are

But Latin does not need to repeat esse at the end. It is understood from the comparison.

So:

• tam prudentes esse quam parentes eorum

naturally means:

• to be as wise as their parents

Not really. Latin word order is much freer than English word order.

This sentence is arranged quite naturally:

• Avunculus first: the topic, the person speaking
• dicit early: tells you the main action
• then the whole indirect statement
• eorum at the end: a common place for a genitive like of them

English depends heavily on word order for grammar. Latin depends much more on word endings, so authors can move words around for emphasis or style.

Strictly speaking, avunculus means mother’s brother, that is, a maternal uncle.

Latin also has:

• patruus = father’s brother

English usually just says uncle, but Latin can be more specific.

No. These words can also mean:

• nepos = grandson or nephew
• neptis = granddaughter or niece

So the exact meaning depends on context.

That is a common vocabulary issue for English speakers, because English normally uses different words for those relationships, while Latin may use the same word in more than one sense.