Lustrum censum finit.

It is a simple subject + object + verb sentence:

• lustrum = the subject
• censum = the direct object
• finit = the verb

So the core idea is: X ends Y.

We know mainly from case.

• censum is clearly accusative singular, so it is the direct object.
• lustrum is the subject here.

A small wrinkle: because lustrum is a neuter noun, its nominative and accusative singular have the same form. So by form alone, lustrum could be either nominative or accusative. But since censum is already the object, lustrum is understood as the subject.

Because censum is the accusative singular form of the noun census.

The noun is fourth declension:

• nominative singular: census
• accusative singular: censum

Since it is the direct object of finit, Latin puts it in the accusative.

Finit is:

• 3rd person singular
• present tense
• active voice
• indicative mood

It comes from finio, finire, meaning to end, to finish, or to bring to a close.

So finit means he/she/it ends or finishes.

In this sentence, ends, finishes, and concludes are all good translations.

The basic idea of finio is to set an end or boundary to something. In context, concludes may sound especially natural in English.

Because Latin word order is much more flexible than English word order.

Latin often puts the verb at or near the end, especially in straightforward prose. So Lustrum censum finit is a very normal Latin arrangement.

English relies heavily on word order to show who is doing what. Latin relies much more on endings.

Yes. Latin could rearrange them, for example:

• Censum lustrum finit
• Finit lustrum censum
• Censum finit lustrum

The basic meaning would stay the same, because the endings still show the roles. But the emphasis or style might change.

In Roman usage, lustrum originally refers to a purificatory rite associated with the completion of the census. By extension, it can also mean the five-year period between censuses.

In this sentence, it most naturally means the lustrum rite or the act that brings the census to its close.

Yes. That is a very common later meaning.

The connection is historical: since the census and its closing rite were associated with a regular cycle, lustrum came to mean a five-year period.

So a learner should know both meanings:

• lustrum = the purification/closing rite
• lustrum = a period of five years

In this sentence, the first sense fits best.

• lustrum is second declension neuter
• census is fourth declension masculine

That is why their forms look different:

• second declension neuter nominative/accusative singular often ends in -um
• fourth declension accusative singular often also ends in -um

So even though both words end in -um here, they belong to different declensions and play different roles.

Because Latin has no articles.

There is no separate word for the or a/an. Latin simply says lustrum censum finit, and English adds the if the context calls for it.

So depending on context, you might translate:

• The lustrum ends the census
• A lustrum ends a census

Usually, context makes the the better choice.

Yes. English census comes directly from Latin census.

So this sentence is a nice example of a Latin word that has passed into English, even though the Latin grammar is different.

Yes. Depending on how literally or naturally you want to translate it, you could say:

• The lustrum ends the census.
• The lustrum concludes the census.
• The purification rite brings the census to an end.
• The lustrum marks the close of the census.

All of these reflect the same basic Latin structure.