La aktoro parolas trankvile.

La is the definite article, meaning the.

So:

• la aktoro = the actor
• aktoro = an actor / actor depending on context

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

The ending -o marks a noun in Esperanto.

So aktoro is a noun meaning actor.

This is a very common Esperanto pattern:

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

Because of this, Esperanto words are often easy to identify by their endings.

The ending -as shows that the verb is in the present tense.

So:

• parolas = speaks / is speaking
• parolis = spoke
• parolos = will speak
• paroli = to speak

Esperanto verbs do not change according to the subject. That means:

• mi parolas = I speak
• vi parolas = you speak
• li parolas = he speaks
• ili parolas = they speak

The verb stays parolas in every case.

Trankvile is an adverb, and adverbs in Esperanto usually end in -e.

Here it describes how the actor speaks:

• trankvile = calmly / quietly / peacefully

Compare:

• trankvila aktoro = a calm actor
  (trankvila is an adjective describing the noun)
• la aktoro parolas trankvile = the actor speaks calmly
  (trankvile is an adverb describing the verb)

So the -e ending is used because it modifies parolas, not aktoro.

Yes. Esperanto word order is fairly flexible.

These are all possible:

• La aktoro parolas trankvile.
• La aktoro trankvile parolas.
• Trankvile parolas la aktoro.

The most neutral and common version is usually:

• La aktoro parolas trankvile.

Changing the order can shift emphasis, but the basic meaning stays the same.

In this sentence, aktoro is the subject, but it does not need any extra marking because there is no direct object here.

Esperanto uses -n for the direct object, not for the subject.

For example:

• La aktoro vidas la hundon. = The actor sees the dog.

Here:

• la aktoro = subject
• la hundon = direct object, marked by -n

In La aktoro parolas trankvile, there is no direct object, so no -n is needed anywhere.

Traditionally, aktoro means actor, and in many contexts it can be used as a general word for a performer, though many learners notice the historically male flavor.

A specifically female form is:

• aktorino = actress

That uses the suffix -in-, which marks female sex:

• patro = father
• patrino = mother

In modern usage, some speakers prefer more gender-neutral wording when possible, but aktoro and aktorino are both common forms to know.

A simple pronunciation guide is:

• tran-KVI-le

Some helpful points:

• a sounds like the a in father
• e sounds like the e in bed but often a bit purer
• stress in Esperanto is usually on the second-to-last syllable

So in tran-kvi-le, the stress falls on kvi.

A rough guide is:

• la ak-TO-ro pa-RO-las tran-KVI-le

Esperanto stress normally falls on the penultimate syllable:

• aktoro → ak-TO-ro
• parolas → pa-RO-las
• trankvile → tran-KVI-le

Also:

• r is usually rolled or tapped
• each vowel is pronounced clearly
• spelling is very regular, so pronunciation is much more predictable than in English

Yes. The Esperanto present tense often covers both ideas.

So parolas can mean:

• speaks
• is speaking
• sometimes even does speak, depending on context

Esperanto usually does not force the same tense distinction that English does between simple present and present progressive. Context tells you which meaning is intended.