Arca vetus cinerem non continet, sed epistulas et stolam.

Vetus means old, and it agrees with arca in case, number, and gender:

• arca = feminine singular nominative
• vetus = feminine singular nominative here

So arca vetus means the old chest or an old chest.

A useful thing to notice is that vetus is a third-declension adjective, so it does not look like a first/second-declension adjective such as bonus, bona, bonum. Its forms are different from what many beginners first expect.

Because cinerem is in the accusative singular. It is the direct object of continet.

The verb continet means contains / holds, so the thing being contained is put in the accusative:

• arca vetus cinerem non continet
• the old chest does not contain ash

The base noun is cinis (ash, ashes), and cinerem is its accusative singular form.

For the same reason: they are also things that the chest contains, so they are direct objects of continet.

• epistulas = accusative plural of epistula (letters)
• stolam = accusative singular of stola (robe / dress / garment)

So the sentence contrasts one object with others:

• not ash
• but letters and a robe

Because the subject is singular: arca vetus.

• arca vetus = the old chest
• continet = contains

Even though epistulas et stolam has more than one thing in it, that does not affect the verb number, because those words are objects, not the subject.

Non simply negates the verb:

• continet = contains
• non continet = does not contain

In Latin, non usually comes before the word or phrase it negates, and here it negates the whole verbal idea.

Sed means but. It introduces a contrast:

• cinerem non continet
• sed epistulas et stolam

So the sentence means something like:

• The old chest does not contain ash, but letters and a robe.

This is a very common Latin pattern:

• non X, sed Y
• not X, but Y

Classical Latin has no articles like English the and a/an.

So:

• arca can mean a chest or the chest
• epistulas can mean letters or the letters
• stolam can mean a robe or the robe

Which one sounds best depends on context. Latin often leaves that for the reader to infer.

Yes. Latin word order is much freer than English word order because the endings show each word’s function.

For example, these would still mean essentially the same thing:

• Arca vetus cinerem non continet, sed epistulas et stolam.
• Cinerem arca vetus non continet, sed epistulas et stolam.
• Epistulas et stolam, sed non cinerem, arca vetus continet.

However, word order still affects emphasis and style. The given sentence is straightforward and natural.

Because the sentence is talking about:

• ash as one mass or quantity, so singular cinerem
• letters as multiple individual items, so plural epistulas

This is about meaning, not grammar alone. Latin often uses singular nouns for materials or substances when English might use ash or ashes depending on context.

Vetus is a third-declension adjective meaning old.

Some important forms are:

• nominative singular masculine/feminine: vetus
• nominative singular neuter: vetus
• genitive singular: veteris

So it does not decline like bonus, bona, bonum. That is why beginners often pause when they see arca vetus instead of something that looks more like arca bona.

Because it is understood from the first part.

The full sense is:

• The old chest does not contain ash, but it does contain letters and a robe.

Latin often leaves out a repeated verb when it is obvious. This is normal and efficient.

If Latin repeated it, the sentence would be heavier and less elegant.

They are two coordinated direct objects joined by et (and):

• epistulas = letters
• stolam = a robe
• epistulas et stolam = letters and a robe

So the chest contains both things. The structure is:

• not
  • object 1
• but
  • object 2 and object 3

That is a very common Latin way to organize contrast.

Either is possible in Latin by itself.

Because Latin has no article, arca vetus could mean:

• the old chest
• an old chest

The surrounding context decides which is best in translation. If this chest has already been mentioned, English would probably use the old chest. If it is being introduced for the first time, English might use an old chest.