Codicilli legatum novum continent.

Codicilli is the subject.

You can tell because continent means they contain, so the verb is plural. Codicilli matches that as a nominative plural noun.

Because continent is 3rd person plural present active indicative.

A quick comparison:

• continet = he/she/it contains
• continent = they contain

The ending -nt is the important clue here.

It is the direct object of the verb, so it is accusative singular.

The codicils are doing the action, and the new legacy/bequest is the thing being contained. That makes legatum novum the object.

One small complication: because legatum is neuter, its nominative singular and accusative singular look the same. So the form by itself could be either one. In this sentence, though, it must be accusative because codicilli is already the subject and continent is a transitive verb.

Because novum is an adjective modifying legatum, and Latin adjectives must agree with the nouns they describe in:

• gender
• number
• case

So:

• legatum = neuter, singular, accusative
• novum = neuter, singular, accusative

That is why the adjective is novum.

We know because of agreement.

Novum is neuter singular accusative, which matches legatum.

But codicilli is masculine plural nominative, so an adjective describing it would have to be something like novi, not novum.

So the grammar clearly shows that novum modifies legatum.

Yes. By itself, codicilli could also be genitive singular.

But in this sentence it cannot be genitive singular, because:

• the verb continent is plural
• the sentence needs a plural subject
• codicilli fits perfectly as nominative plural

So here it means codicils, not of the codicil.

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

That means a Latin phrase such as legatum novum can be translated as:

• a new legacy
• the new legacy

Which one is best depends on the context.

Not as much as it would be in English.

Latin uses endings much more than word order to show who is doing what. So this sentence can be understood even if the words are rearranged.

The order here is perfectly normal, and putting the verb continent at the end is especially common in Latin.

So the meaning comes mainly from the forms:

• codicilli = subject
• legatum novum = object
• continent = verb

Here are the usual dictionary forms:

• codicillus, -i = codicil
• legatum, -i = legacy, bequest
• novus, -a, -um = new
• contineo, continere, continui, contentum = contain

Knowing dictionary forms helps you recognize how the words have been inflected in the sentence.