La prunto havas interezon.

Because havi means to have, while esti means to be.

So:

• La prunto havas interezon. = The loan has interest.
• La prunto estas interezo. would mean The loan is interest, which is a completely different idea.

In this sentence, interest is something connected to the loan, so Esperanto uses havas.

The -n ending marks the direct object in Esperanto.

Here:

• La prunto = the subject
• havas = has
• interezon = the thing being had, so it is the direct object

That is why it is interezon, not interezo.

La is the definite article, meaning the.

• La prunto = the loan
• interezon = interest / an interest charge in a more general sense

So the sentence talks about a specific loan, but does not necessarily specify a particular interest amount. If you wanted to make both nouns definite, you could say:

• La prunto havas la interezon...

But that usually sounds less natural unless you mean some specific, already-known interest.

Prunto means a loan.

It comes from the idea of lending/borrowing. Related words include:

• prunti = to lend / to loan
• prunte = on loan

So La prunto means The loan.

This is a very useful distinction in Esperanto:

• intereso = interest in the sense of curiosity, concern, attention
• interezo = financial interest

So:

• Mi havas intereson pri lingvoj. = I have an interest in languages.
• La prunto havas interezon. = The loan has interest.

That z is important.

Yes, it is understandable and correct.

It means that the loan carries interest or is not interest-free.

Depending on context, Esperanto speakers might also say things like:

• La prunto estas intereza. = The loan is interest-bearing.
• La prunto portas interezon. = The loan carries interest.
• La prunto havas interezan tarifon. = The loan has an interest rate.

But La prunto havas interezon is perfectly fine.

Normally, no. Financial interest is usually treated as an uncountable or mass idea here, so singular is the natural choice:

• interezon

You would use plural only in a special context, for example if you meant multiple separate interest charges or kinds of interest.

Here is the breakdown:

• La = the definite article
• prunto = noun, loan
• havas = present tense of havi, has
• interezon = noun, interest, with -n because it is the direct object

So the structure is:

article + subject noun + verb + object noun

In Esperanto, -as marks the present tense.

So:

• havas = has / have
• havis = had
• havos = will have

Because the sentence is in the present, Esperanto uses havas.

Grammatically, yes, but the meaning changes a little.

• La prunto havas interezon. = The loan has interest.
• Prunto havas interezon. = A loan has interest or Loans have interest, depending on context

So if you are talking about one specific loan, la is the natural choice.

Yes. In many contexts, that is exactly the point.

La prunto havas interezon suggests that interest is charged on the loan. In other words, it is not a senintereza prunto:

• senintereza prunto = interest-free loan

So this sentence can be used to contrast a normal loan with an interest-free one.