Pueri circa focum sedent, dum avia fabulam narrat.

Pueri is the nominative plural of puer, meaning boy. It is nominative because it is the subject of sedent (sit), and it is plural because more than one boy is involved.

Focum is accusative because it follows the preposition circa, which regularly takes the accusative case.
So:

• focus = hearth, fireplace
• circa focum = around the hearth

Even though English uses around without changing the noun, Latin shows the relationship by putting the noun into the accusative.

Circa means around or about in a physical sense here. In this sentence, circa focum sedent means they are sitting around the hearth.

It is a preposition, and in this use it takes the accusative.

Sedent is the 3rd person plural present active indicative of sedere, meaning to sit.

It is plural because the subject is pueri (the boys).

So:

• sedeo = I sit
• sedes = you sit
• sedet = he/she sits
• sedent = they sit

Dum here means while. It connects the two actions:

• the boys are sitting around the hearth
• while grandmother is telling a story

So it introduces an action happening at the same time as the main action.

Avia is nominative because it is the subject of narrat (tells).
In other words, grandmother is the one doing the telling.

So:

• avia = grandmother
• avia narrat = grandmother tells

Fabulam is accusative because it is the direct object of narrat. It is the thing being told.

So:

• fabula = story, tale
• fabulam narrat = she tells a story

This is very common in Latin: the direct object usually appears in the accusative case.

Narrat is the 3rd person singular present active indicative of narrare, meaning to tell or to relate.

It is singular because the subject, avia, is singular.

So avia fabulam narrat means grandmother tells a story.

Latin often uses the simple present tense where English might use either the simple present or the present progressive.

So:

• sedent can mean they sit or they are sitting
• narrat can mean she tells or she is telling

The context determines which English translation sounds more natural.

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

This sentence has:

• Pueri = subject
• circa focum = prepositional phrase
• sedent = verb
• dum avia fabulam narrat = subordinate clause

A different order could still make sense in Latin, as long as the forms are clear. But this order is natural and easy to understand.

Yes. Latin has no articles like English a/an and the. So fabulam could mean either a story or the story, depending on context.

In a standalone sentence like this, English often chooses a story unless the context has already identified a particular story.

Both sedent and narrat are in the present tense because the sentence describes two actions happening at the same time:

• the boys are sitting
• grandmother is telling a story

The conjunction dum helps show this simultaneity: while grandmother tells / is telling a story.