La produkto havas garantion de du jaroj.

Because garantion is the direct object of havas.

In Esperanto, the thing that is had, seen, bought, etc. usually gets the accusative ending -n.

• La produkto havas garantion. = The product has a warranty.
• La produkto havas prezon. = The product has a price.

So garantio becomes garantion because it is what the product has.

Here de links the noun garantion with its length or measure.

So garantion de du jaroj means something like:

• a warranty of two years
• a two-year warranty

This is a normal way to describe a noun by its duration or size.

A native English speaker might expect dum, but dum is used more with actions or situations over time, not usually directly after a noun like this.

Compare:

• La produkto havas garantion de du jaroj. = The product has a two-year warranty.
• La garantio validas dum du jaroj. = The warranty is valid for two years.

Because Esperanto normally uses the plural after numbers greater than one.

So:

• unu jaro = one year
• du jaroj = two years
• tri jaroj = three years

That is why the sentence has du jaroj.

Because jaroj is inside the prepositional phrase de du jaroj.

After a preposition like de, nouns normally do not take the accusative -n just because of the preposition.

So:

• garantion gets -n because it is the direct object
• jaroj does not get -n because it is part of de du jaroj

If you said du jarojn, that would be a different structure, usually marking duration directly, not a de phrase.

Yes. That is very natural Esperanto.

• dujara garantio = a two-year warranty

So you could say:

• La produkto havas dujaran garantion.

Notice that dujara is an adjective, and because it describes the direct object garantion, it also takes -n:

• dujara → dujaran

Many learners find this version very elegant because it matches English two-year warranty closely.

La is the definite article, meaning the.

So la produkto means the product, not just a product or product in general.

You use la when the speaker and listener are thinking of a specific product.

Compare:

• La produkto havas garantion de du jaroj. = The product has a two-year warranty.
• Produkto havas garantion de du jaroj. = This sounds less natural and more generic.
• Produktoj havas garantion de du jaroj. = Products have a two-year warranty.

Yes. Havi is a very normal and simple way to say that something comes with or includes a feature.

So La produkto havas garantion de du jaroj is clear and correct.

Other natural possibilities include:

• La produkto venas kun dujara garantio. = The product comes with a two-year warranty.
• La produkto inkluzivas dujaran garantion. = The product includes a two-year warranty.

But havas is perfectly good basic Esperanto.

It describes garantion.

It tells you what kind of warranty it is: one whose length is two years.

So the structure is:

• La produkto = the product
• havas = has
• garantion = a warranty
• de du jaroj = of two years

In other words, de du jaroj is attached to garantion, not to havas.

In many contexts, yes. Garantio can cover the general idea of a guarantee or warranty.

In a product sentence like this, English often translates it as warranty:

• La produkto havas garantion de du jaroj. = The product has a two-year warranty.

So even if the dictionary gives guarantee, the product-related meaning warranty is often the best choice in context.

Yes, Esperanto word order is somewhat flexible, but the normal order here is the clearest:

• La produkto havas garantion de du jaroj.

Because garantion has the accusative -n, Esperanto can sometimes move it for emphasis. But for learners, the standard subject-verb-object order is best.

So this sentence is a very good, natural default pattern to use.