Cum cena parata est, familia in triclinium venit.

Here cum means when.

It introduces a clause that gives the time of the main action:

• Cum cena parata est = When the meal has been prepared / When dinner is ready

In other contexts, cum can also mean with, but not here.

Because cum can be used in two different ways in Latin:

• as a preposition meaning with:
  
  • cum amico = with a friend
• as a conjunction meaning when, since, or although:
  
  • cum venit = when he came

In this sentence, cum is followed by a whole clause, cena parata est, not by a noun in the ablative. That shows it is the conjunction when.

The subject is cena.

• cena = the meal / dinner
• est = is

So literally, cena parata est means the meal is prepared or more naturally the meal has been prepared / dinner is ready.

Because parata agrees with cena.

Latin adjectives and participles must match the noun they describe in:

• gender
• number
• case

Here:

• cena is feminine singular nominative
• so parata must also be feminine singular nominative

That is why it is parata.

Parata est is a perfect passive form.

It is made of:

• parata = the perfect passive participle of paro (prepare)
• est = is

Together they mean:

• has been prepared
• or idiomatically is ready

So cena parata est literally means the meal has been prepared.

Because Latin forms the perfect passive with:

• a perfect passive participle
• plus a present form of sum

So:

• parata est = has been prepared

Even though est by itself means is, the whole expression does not mean simple present here. The participle changes the meaning of the whole verb phrase.

Familia is nominative singular because it is the subject of venit.

• familia = the family
• venit = comes / came

So familia is the one doing the action.

Because in with the accusative often shows motion into something.

• in triclinium = into the dining room

Compare:

• in triclinium venit = she/he/it came into the dining room
• in triclinio est = she/he/it is in the dining room

So:

• in + accusative = movement toward/into
• in + ablative = location in/on

A triclinium is a Roman dining room.

Originally the word refers to a room with three couches used for dining, but in many beginner Latin texts it is best understood simply as dining room.

Because venit can be either:

• present tense: comes
• perfect tense: came / has come

These two forms look the same in Latin.

So the exact translation depends on context. In a narrative sentence like this, many learners will understand it as came:

• When dinner was ready, the family came into the dining room.

But comes is also possible if the passage is in present-time narration.

You tell from the context, not from the form alone.

For the verb venio:

• venit can mean he/she/it comes
• venit can also mean he/she/it came

Latin sometimes has forms that are identical in spelling. You must look at the surrounding sentences and the style of the passage to decide which meaning fits.

Latin word order is more flexible because the endings show the grammar.

A very literal order is:

• When the meal prepared is, the family into the dining room comes/came.

That sounds unnatural in English, but Latin can do this because:

• cena is clearly the subject of est
• familia is clearly the subject of venit
• triclinium is marked by in and the accusative

So the meaning does not depend as heavily on word order as it does in English.

Yes. That is a very natural English translation.

Literally it is the meal has been prepared, but idiomatically English often says:

• dinner is ready

That captures the sense well.

It is related, but in Roman culture familia can have a broader meaning than modern English family.

It can refer to:

• the household
• family members
• sometimes even household servants or dependents, depending on context

In a simple sentence like this, the family is the best translation.

Classical Latin has no definite article like English the and no indefinite article like a/an.

So:

• cena can mean meal, a meal, or the meal
• familia can mean family, a family, or the family

You choose the most natural English wording from the context. Here the meal and the family make the most sense.