La kaverno estas apud la akvofalo.

Because la means the, and it is used separately before each noun that is definite.

• la kaverno = the cave
• la akvofalo = the waterfall

In Esperanto, you do not use one la to cover both nouns unless the structure clearly allows it. Here, each noun phrase has its own article.

Also, Esperanto has only a definite article, la. There is no separate word for a or an. So:

• kaverno = a cave or cave
• la kaverno = the cave

The ending -o marks a noun in Esperanto.

So:

• kavern-o = cave
• akvofal-o = waterfall

This is one of the most basic and regular features of Esperanto grammar:

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

A learner can often identify a word’s part of speech just by looking at its ending.

Estas is the present-tense form of esti, meaning to be.

So:

• mi estas = I am
• vi estas = you are
• li estas = he is
• ŝi estas = she is
• ĝi estas = it is
• ili estas = they are

Unlike English, Esperanto verbs do not change according to person or number. The verb form stays the same.

That means estas always means present tense, no matter what the subject is.

Apud means beside, next to, or by.

It usually indicates that something is at the side of something else, or very near it.

So:

• La kaverno estas apud la akvofalo = The cave is beside / next to the waterfall.

A native English speaker may notice that English words like by, near, beside, and next to overlap somewhat. In Esperanto, apud often suggests closeness at the side, not just general nearness.

Compare:

• apud = beside, next to
• proksime de = near, close to
• ĉe = at, by, in the vicinity of

There is no -n because there is no direct object here.

The sentence is made of:

• La kaverno = the subject
• estas = the verb
• apud la akvofalo = a prepositional phrase

In Esperanto, the accusative -n is mainly used for direct objects, and sometimes for motion toward something.

But here:

• kaverno is the subject, so no -n
• akvofalo follows the preposition apud, so normally no -n

So the sentence stays:

• La kaverno estas apud la akvofalo.

not:

• La kavernon...
• ...apud la akvofalon

in this ordinary location meaning.

Yes, Esperanto word order is fairly flexible.

The basic order here is:

• La kaverno estas apud la akvofalo.

But you could also say:

• Apud la akvofalo estas la kaverno.

That might sound a little more like Beside the waterfall is the cave in English. It changes the emphasis, not the core meaning.

Even so, the original word order is the most neutral and beginner-friendly.

Yes. Akvofalo is a compound.

It is made from:

• akvo = water
• falo = fall

So literally it is something like water-fall.

This is very typical in Esperanto. You can often understand a longer word by breaking it into meaningful parts.

For example:

• akvoglaso = water glass
• sunlumo = sunlight
• dormoĉambro = bedroom

In compounds, the main idea usually comes at the end. So akvofalo is a kind of falo related to akvo.

The word is kaverno, the normal Esperanto word for cave.

Many Esperanto roots come from European languages, but they are adapted to Esperanto spelling and word-building rules. You do not always get a form that matches English exactly.

The important thing for a learner is to recognize:

• kavern- = the root
• -o = noun ending

So kaverno is the noun cave.

If you later see related forms, they follow the same regular system:

• kaverna = cave-related, cavernous
• kaverne = in a cave-like way
• kavernoj = caves

Esperanto does not have an indefinite article.

So English a cave or a waterfall is usually expressed simply by the noun without la:

• Kaverno estas apud akvofalo is possible in a purely article-free sense, but in real usage that exact sentence may sound unusual depending on context.

More naturally, Esperanto often relies on context to show whether something is definite or indefinite.

The key contrast is:

• la kaverno = the cave
• kaverno = a cave / cave

In your sentence, la makes both nouns definite and specific.

Yes, very much so.

In this sentence:

• estas = is
• apud = beside / by / next to

Together they express location:

• estas apud = is beside / is next to

This is a normal and very common pattern in Esperanto:

• La domo estas apud la rivero. = The house is beside the river.
• La lernejo estas apud la parko. = The school is next to the park.

So an English speaker can think of it as a simple to be + location phrase structure.

Esperanto pronunciation is very regular. A rough guide is:

• La = lah
• kaverno = kah-VER-no
• estas = ES-tahs
• apud = ah-POOD
• la = lah
• akvofalo = ah-kvo-FAH-lo

A few useful points:

• Stress is always on the second-to-last syllable
  • kaVERno
  • EStas
  • aPUD
  • akvoFAlo
• v is like English v
• a is like a in father
• u is like oo in food

That regular stress system makes Esperanto much easier to pronounce consistently than English.