La satelito ne estas armilo.

La is the definite article, equivalent to English the.

So la satelito means the satellite, not just a satellite.

A useful thing to remember: Esperanto has only one article, la, and it never changes for gender, number, or case. So it stays la in all situations.

In Esperanto, nouns end in -o.

So:

• satelito = satellite
• armilo = weapon

The -o ending tells you right away that the word is a noun. This is one of the most regular features of Esperanto.

Also, because it does not end in -j, it is singular.
If it were plural, it would be satelitoj.

Estas is the present tense of esti, which means to be.

So:

• mi estas = I am
• vi estas = you are
• li estas = he is
• la satelito estas = the satellite is

Unlike English, Esperanto verbs do not change according to the subject. The present tense always ends in -as.

That means estas works for all persons and numbers.

Ne is the normal word for not.

In Esperanto, ne usually comes directly before the thing it negates. In this sentence, it negates the verb phrase:

• La satelito ne estas armilo.
• The satellite is not a weapon.

Putting ne before estas is the standard and natural placement here.

Because armilo is a predicate noun after estas, not a direct object.

The -n ending is usually used for a direct object. But after verbs like esti (to be), the noun that follows describes or identifies the subject; it is not being acted upon.

So:

• La satelito estas armilo. = The satellite is a weapon.
• La satelito ne estas armilo. = The satellite is not a weapon.

No -n is used after estas in this kind of sentence.

Esperanto normally has no indefinite article.

So English a weapon is just:

• armilo

Compare:

• la armilo = the weapon
• armilo = a weapon / weapon, depending on context

If you really want to emphasize one, you can use unu, but that usually means one, not just an ordinary indefinite article.

Yes. Esperanto words are often built from parts.

Armilo can be analyzed as:

• arm- = arm / weapon-related root
• -il- = instrument or tool
• -o = noun

So armilo is literally something like an instrument for arming, which in normal usage means weapon.

This is a very common Esperanto pattern:

• tranĉi = to cut
• tranĉilo = a cutting tool = knife

So seeing -il- often helps you guess that the word is some kind of tool or instrument.

The normal word order here is the straightforward one:

• La satelito ne estas armilo.

That is the most natural way to say it.

Esperanto word order is somewhat flexible, but not every rearrangement sounds equally natural. In a simple sentence like this, keeping ne before the verb and using the usual subject-verb-complement order is best for learners.

So this sentence is a good model to follow.

Yes. To make the nouns plural, Esperanto adds -j.

For example:

• La satelitoj ne estas armiloj.
• The satellites are not weapons.

Notice that:

• satelito → satelitoj
• armilo → armiloj

But the verb stays the same:

• estas

Verbs do not change for singular or plural.

A rough pronunciation is:

• La = lah
• satelito = sah-teh-LEE-toh
• ne = neh
• estas = ESS-tahs
• armilo = ahr-MEE-loh

A few helpful pronunciation points:

• Every vowel is pronounced clearly.
• Stress in Esperanto usually falls on the second-to-last syllable.
• So:
  • sateLIto
  • EStas
  • arMIlo

That regular stress pattern is one of the things that makes Esperanto pronunciation easier to learn.