La asocio mendis novan komputilon.

La is the definite article in Esperanto, like the in English. It shows that the speaker has a specific association in mind: the association.

Esperanto has only one article, la. It does not change for gender, number, or case.

Esperanto has no indefinite article. English distinguishes between a computer and the computer, but Esperanto only marks the definite one with la.

So:

• komputilo = a computer or just computer
• la komputilo = the computer

That is why novan komputilon can mean a new computer without any extra word for a.

The ending -o marks a noun in Esperanto. So asocio is a noun meaning association.

This is one of the most important Esperanto patterns:

• -o = noun
• -a = adjective
• -e = adverb
• -i = infinitive verb

So when you see asocio or komputilo, the -o tells you they are nouns.

The ending -is marks the past tense in Esperanto. So mendis means ordered.

Compare:

• mendi = to order
• mendas = orders / is ordering
• mendis = ordered
• mendos = will order

So La asocio mendis... tells us the action happened in the past.

The -n marks the direct object. The direct object is the thing that receives the action of the verb.

In this sentence:

• La asocio = the subject, the one doing the ordering
• mendis = ordered
• novan komputilon = the thing that was ordered

So komputilon gets -n because it is the direct object.

Because adjectives must agree with the nouns they describe.

Here, nova describes komputilo, and komputilo is:

• singular
• a noun
• in the accusative case (because it is the direct object)

So the adjective must match that. That gives:

• nova komputilo = a new computer
• novan komputilon = a new computer as direct object

Both words take the accusative marking:

• nova → novan
• komputilo → komputilon

Because asocio is the subject, not the object.

In Esperanto, the accusative -n usually marks the direct object, not the subject.

So:

• La asocio mendis novan komputilon. = The association ordered a new computer.

If you put -n on asocio, you would be marking it as an object instead, which would change the grammar.

Not exactly.

• mendi = to order
• aĉeti = to buy

If an association mendis novan komputilon, it placed an order for one. That does not focus on the act of paying for it in the same way aĉeti does.

So mendis is the correct choice if the idea is ordered, not simply bought.

Yes, Esperanto word order is fairly flexible, mainly because the accusative -n shows which noun is the object.

So all of these are grammatically understandable:

• La asocio mendis novan komputilon.
• Novan komputilon mendis la asocio.
• Mendis la asocio novan komputilon.

However, the most neutral and common order is still subject + verb + object, which is the version you were given.

Yes. Esperanto words are often built from smaller meaningful parts.

komputilo can be analyzed as:

• komput- = compute
• -il- = tool or instrument
• -o = noun

So komputilo literally means something like a computing tool, which corresponds to computer.

This kind of word-building is very common in Esperanto and is one of its most useful features for learners.