Ŝi volas adopti katon.

In Esperanto, ŝ is a separate letter, pronounced like sh in she. So ŝi sounds roughly like shee.

This matters because s and ŝ are different sounds and can change the word completely. Esperanto spelling is very regular, so each letter has one consistent pronunciation.

In Esperanto, all present-tense verbs end in -as. So volas means it is in the present tense.

A useful pattern is:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command / jussive
• -i = infinitive

So volas is simply the present-tense form of the verb voli.

Because adopti is an infinitive, like to adopt in English.

After verbs like voli (to want), Esperanto normally uses an infinitive:

• Mi volas manĝi. = I want to eat.
• Ŝi volas adopti katon. = She wants to adopt a cat.

So volas is the main conjugated verb, and adopti stays in the basic infinitive form.

In Esperanto, the infinitive ending -i already does the job that English often expresses with to.

So:

• adopti = to adopt
• manĝi = to eat
• iri = to go

You do not add another word before it.

The -n marks the direct object. It shows which noun receives the action of the verb.

Here, the action is adopti, and the thing being adopted is the cat, so kato becomes katon.

This is called the accusative ending.

Compare:

• La kato dormas. = The cat is sleeping.
  The cat is the subject, so no -n.
• Ŝi vidas la katon. = She sees the cat.
  The cat is the object, so it gets -n.

Yes, in normal Esperanto, Ŝi volas adopti kato would be ungrammatical.

Because kato is the thing being adopted, it must be marked as the direct object with -n: katon.

Esperanto relies on that ending very consistently.

Esperanto has la for the, but it has no indefinite article like English a/an.

So:

• kato can mean a cat or just cat, depending on context
• la kato means the cat

That means katon by itself is often understood as a cat in a sentence like this, unless the context makes it specific.

Normally, if you mean the cat, you would say la katon.

So:

• Ŝi volas adopti katon. = usually She wants to adopt a cat
• Ŝi volas adopti la katon. = She wants to adopt the cat

Without la, the noun is usually indefinite or non-specific.

No, Esperanto word order is fairly flexible because endings show grammatical roles.

The most neutral order is:

• Ŝi volas adopti katon.

But other orders are possible for emphasis, for example:

• Katon ŝi volas adopti.

Because katon has the -n, you still know it is the object.

That said, beginners should usually stick with the normal subject-verb-object pattern unless they have a reason to change it.

Normally, Esperanto uses the subject pronoun when it is needed, so ŝi is standard here.

Because volas does not change depending on the person, the verb alone does not tell you whether the subject is I, you, she, they, and so on. For that reason, Esperanto usually keeps the pronoun:

• Mi volas
• Vi volas
• Ŝi volas
• Ili volas

So in a normal standalone sentence, ŝi should be there.

A simple approximate pronunciation for an English speaker is:

SHEE VOH-lahs ah-DOP-tee KAH-ton

A few details:

• ŝi = shee
• volas = VOH-lahs
• adopti = ah-DOP-tee
• katon = KAH-ton

Esperanto stress is very regular: it falls on the second-to-last syllable of each word.

So:

• Ŝi → only one syllable
• vo-las → stress on vo
• a-dop-ti → stress on dop
• ka-ton → stress on ka