La dentisto klarigis ne nur la anestezon, sed ankaŭ la injekton.

The -n ending marks the direct object in Esperanto.

In this sentence, the thing being explained is la anestezon and la injekton, so both nouns take -n:

• La dentisto klarigis la anestezon.
• La dentisto klarigis la injekton.

Because klarigis is a transitive verb, it needs an object: the dentist explained what? The anesthesia and the injection.

Ne nur ... sed ankaŭ ... means not only ... but also ...

So:

• ne nur la anestezon = not only the anesthesia
• sed ankaŭ la injekton = but also the injection

It links two parallel parts of the sentence. Here, both linked parts are direct objects.

A simpler pattern is:

• Mi volas ne nur kafon, sed ankaŭ teon.
  • I want not only coffee, but also tea.

The important thing is that the two parts should match in function. In your sentence, both are nouns in the accusative.

Esperanto often uses la when talking about specific things already known in the situation.

Here, the sentence is talking about two specific things connected with the dental visit:

• la anestezon
• la injekton

Using la before both nouns makes each one definite. In English, we might also say the anesthesia and the injection.

You usually repeat la when each noun is separately part of the structure:

• ne nur la X, sed ankaŭ la Y

That sounds natural and clear.

Klarigis is in the past tense.

In Esperanto:

• -as = present
• -is = past
• -os = future

So:

• klarigas = explains / is explaining
• klarigis = explained
• klarigos = will explain

The verb stem here is klarig-, and the -is tells you it happened in the past.

Because klarigi means to make clear, to explain.

This comes from:

• klara = clear
• klarigi = to clarify, explain

The suffix -ig- often means to cause or make. So klarigi is literally something like to make clear.

Compare:

• La afero estas klara. = The matter is clear.
• La dentisto klarigis la aferon. = The dentist explained the matter.

So klarigis is exactly the right form for explained.

Dentisto means dentist.

It is built from:

• dent- = tooth
• -ist- = a person professionally involved with something
• -o = noun ending

So dentisto is literally a tooth-professional.

The suffix -ist- is common in profession words, for example:

• pianisto = pianist
• verkisto = writer
• artisto = artist

Yes, basically. Anestezo is the Esperanto word for anesthesia/anaesthesia.

Depending on context, it can refer to:

• the state of numbness or loss of sensation
• the anesthetic procedure
• sometimes the anesthetic effect being discussed

In a dental context, it makes sense as something the dentist would explain before treatment.

They are related, but not identical.

• anestezo = the anesthesia, the numbing procedure/effect
• injekto = the injection, the shot itself

So the sentence suggests the dentist explained both:

1. the anesthesia itself, and
2. the injection used for it

That distinction is natural in a medical or dental setting.

Yes, Esperanto allows some flexibility, but sed ankaŭ la injekton is a very natural placement.

In this pattern, ankaŭ usually comes right before the thing being added:

• sed ankaŭ la injekton

That clearly means but also the injection.

If you move ankaŭ, the emphasis can change slightly, and some placements may sound less natural. For learners, the safest pattern is:

• ne nur X, sed ankaŭ Y

Yes, and that is exactly what happens here. The verb klarigis applies to both objects.

Fuller version:

• La dentisto klarigis ne nur la anestezon, sed ankaŭ la injekton.

This means the same as something like:

• La dentisto klarigis la anestezon kaj ankaŭ klarigis la injekton.

But repeating the verb would be unnecessary and less elegant. Esperanto, like English, often leaves it unstated when it is understood.

Because klarigi directly takes an object in Esperanto.

So Esperanto says:

• klarigi ion = to explain something

Examples:

• Ŝi klarigis la planon. = She explained the plan.
• La dentisto klarigis la injekton. = The dentist explained the injection.

English sometimes uses explain directly and sometimes adds words like about, but Esperanto normally uses the direct object here.

Yes. Esperanto word order is fairly flexible, as long as the structure stays clear.

For example, this is also possible:

• La dentisto ne nur klarigis la anestezon, sed ankaŭ la injekton.

That version shifts the focus slightly onto the action klarigis. The original sentence puts the contrast directly on the objects:

• not only the anesthesia
• but also the injection

Both are understandable, but the original is especially clear if the goal is to contrast the two things explained.

A rough English-friendly guide:

• La = lah
• dentisto = den-TEE-sto
• klarigis = klah-ree-GEES
• ne = neh
• nur = noor
• la = lah
• anestezon = ah-ნეს-teh-ZON
• sed = sed
• ankaŭ = ahn-KOW
• la = lah
• injekton = een-YEK-ton

A few useful pronunciation notes:

• Stress is always on the second-to-last syllable:
  • denTISto
  • klariGIS
  • anesteZON
  • inYEKton
• j sounds like English y
• kaŭ sounds roughly like kow

That regular stress system makes Esperanto pronunciation much easier once you get used to it.