Ne malpaku la duan produkton.

Malpaku comes from:

• pak- = the idea of packing
• -i = the infinitive ending, so paki = to pack
• mal- = a prefix meaning the opposite

So malpaki means to unpack.

Then -u changes it into a command or instruction. So malpaku means unpack!

Esperanto often builds words this way, so long-looking words are often very systematic.

No, it is not a double negative.

• mal- is not the same as English not
• mal- is a word-building prefix meaning opposite
• ne is the actual grammatical negation, meaning not

So:

• paku = pack!
• malpaku = unpack!
• ne malpaku = do not unpack!

In other words, ne negates the whole command, while mal- is just part of the verb’s meaning.

The ending -u is the Esperanto form used for:

• commands
• requests
• instructions
• wishes

So malpaku is a command: unpack!

Compare:

• malpaki = to unpack
• malpakas = is unpacking / unpacks
• malpakis = unpacked
• malpakos = will unpack
• malpaku = unpack!

In this sentence, -u is used because someone is being told what not to do.

Yes. The subject is understood.

In Esperanto, commands often leave out vi = you, just like English often does:

• Sit down.
• Don’t open it.

Esperanto does the same:

• Malpaku. = Unpack.
• Ne malpaku. = Don’t unpack.

So the full idea is essentially You, do not unpack the second product, but vi is normally omitted.

The -n marks the direct object.

The direct object is the thing directly affected by the action. Here, the action is unpacking, and the thing being unpacked is the second product.

So:

• produkto = product
• produkton = product as a direct object

Esperanto uses -n for direct objects very regularly, which is one reason word order can be flexible.

Because adjectives in Esperanto must agree with the nouns they describe.

Since produkton is:

• singular
• accusative

the adjective must also be:

• singular
• accusative

So:

• dua produkto = second product
• duan produkton = second product as a direct object

Both the adjective and the noun take -n in the accusative.

La is the definite article, meaning the.

So la duan produkton means the second product, not just a second product.

Unlike adjectives and nouns, la never changes:

• not for singular or plural
• not for accusative
• not for gender

So it stays la in every situation.

No, that would mean something different.

• Ne paku la duan produkton = Do not pack the second product
• Ne malpaku la duan produkton = Do not unpack the second product

This is an important distinction:

• paki = pack
• malpaki = unpack

So the prefix mal- changes the verb’s meaning, and ne then negates that new verb.

Yes, to some extent.

The most neutral order is:

• Ne malpaku la duan produkton.

Because -n marks the object, Esperanto can sometimes move things around for emphasis, for example:

• La duan produkton ne malpaku.

That still means the same basic thing, but it puts more emphasis on the second product.

For a learner, though, the original order is the safest and most natural one to use.