Ambo nepotes avunculi fabulam de mari libenter audiunt.

Ambo means both, while duo means two.

So:

• ambo nepotes = both grandsons/nephews
• duo nepotes = two grandsons/nephews

Latin uses ambo when it wants to emphasize the pair as a complete set, just like English both.

Here ambo is:

• nominative
• masculine
• plural

It agrees with nepotes, the noun it goes with.

So ambo nepotes means both grandsons/nephews and both words are in the same case, number, and gender.

You can tell from both the noun form and the verb:

• nepotes is nominative plural
• audiunt means they hear / they listen

So nepotes is the thing doing the action.

A very literal structure is:

• Ambo nepotes avunculi = both grandsons/nephews of the uncle
• fabulam de mari = a story about the sea
• libenter audiunt = gladly listen to / hear

Because avunculi here is genitive singular.

The genitive often shows possession or close connection, so:

• avunculi = of the uncle

That means nepotes avunculi is the uncle’s grandsons/nephews or more literally grandsons/nephews of the uncle.

A learner often notices that avunculi could also look like nominative plural, but here the sentence makes best sense if it is genitive singular.

Fabulam is accusative singular.

It is the direct object of audiunt, because it is the thing being heard:

• they hear the story

So:

• audiunt = they hear / listen to
• fabulam = the story being heard

The preposition de takes the ablative case.

So:

• de = about / concerning / from / down from, depending on context
• mari = ablative singular of mare = sea

In this sentence, with fabulam, de mari means about the sea.

So fabulam de mari = a story about the sea.

Libenter is an adverb. It means:

• gladly
• willingly
• with pleasure

It describes how they listen.

So:

• audiunt = they listen
• libenter audiunt = they gladly listen

Because it is an adverb, it does not change form to agree with a noun.

Audiunt is:

• present tense
• active voice
• indicative mood
• third person plural

from the verb audire = to hear, listen to

So audiunt means:

• they hear
• they are listening to
• often simply they listen to, depending on context

The -unt ending tells you the subject is they.

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

This sentence is ordered:

• Ambo nepotes avunculi
• fabulam de mari
• libenter audiunt

But Latin could rearrange many of these words without changing the basic meaning, for example:

• Fabulam de mari ambo nepotes avunculi libenter audiunt.
• Ambo avunculi nepotes fabulam de mari audiunt libenter.

The original order is perfectly natural and keeps related words grouped clearly, but the endings matter more than the position.

Classical Latin does not have articles like English the and a/an.

So:

• fabulam can mean a story or the story
• avunculi can mean of an uncle or of the uncle

The exact sense usually comes from context.

That is why a Latin sentence can be shorter than its English translation.

Nepos, nepotis can mean grandson or descendant, and in some contexts it can also be understood as nephew.

So the exact English word depends on context and on the meaning your course or teacher has given for the sentence.

For grammar purposes here, the important points are:

• nepotes is plural
• it is nominative here
• it is the subject of audiunt

Yes. That is a very good way to read Latin.

You can divide it like this:

• Ambo nepotes avunculi = the subject phrase
• fabulam de mari = the object phrase
• libenter audiunt = the verb phrase

That helps you see the structure:

• Who? both grandsons/nephews of the uncle
• What do they hear? a story about the sea
• How? gladly

This kind of chunking is often easier than translating word by word.