Li diris la veron, ĉar li ne volis mensogi antaŭ la infanoj.

Because la veron is the direct object of diris.

In Esperanto, direct objects usually take the ending -n:

• vero = truth
• la vero = the truth
• la veron = the truth, as the thing being told

So Li diris la veron means He told the truth. The -n is required here.

Diris is the past tense of diri, meaning to say or to tell.

Esperanto verb endings are very regular:

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

So:

• diri = to say
• diras = says / is saying
• diris = said

Because ĉar introduces a new clause, and that clause needs its own subject.

So the sentence has two parts:

• Li diris la veron
• ĉar li ne volis mensogi antaŭ la infanoj

The second li means he again, and Esperanto normally does not omit the subject the way some languages do. Repeating it is completely normal.

Ĉar means because. It introduces the reason for the action in the main clause.

So:

• Li diris la veron = he told the truth
• ĉar li ne volis mensogi antaŭ la infanoj = because he did not want to lie in front of the children

It is a conjunction, just like because in English.

The comma separates the main clause from the subordinate clause.

Here:

• main clause: Li diris la veron
• subordinate clause: ĉar li ne volis mensogi antaŭ la infanoj

A comma before ĉar is very common and natural in Esperanto writing. It helps show the structure clearly.

Because after voli = to want, Esperanto normally uses the infinitive.

So:

• voli = to want
• mensogi = to lie
• volis mensogi = wanted to lie / did not want to lie, depending on ne

In this sentence:

• ne volis mensogi = did not want to lie

This is similar to English wanted to lie, where to lie is also not finite.

Yes, it means to tell a falsehood.

This is helpful because English lie has two meanings:

• to lie = to tell something false
• to lie down = to recline

Esperanto avoids that ambiguity:

• mensogi = to tell a lie
• kuŝi = to lie down

So in this sentence, mensogi clearly means to tell a lie.

Literally, antaŭ often means before or in front of.

In this sentence, antaŭ la infanoj means something like:

• in front of the children
• in the presence of the children

So the idea is that he did not want to lie where the children would hear or see it.

Because after a preposition like antaŭ, you normally do not use -n unless you want to show motion toward something.

Here there is no movement. It is just location or presence:

• antaŭ la infanoj = in front of the children / before the children

A form with -n after a preposition is used for direction in some cases, but that is not what is happening here.

La makes the noun definite: the children.

So:

• infanoj = children
• la infanoj = the children

The sentence is talking about a specific group of children, not children in general. That is why la is used.

The ending -j marks the plural.

So:

• infano = child
• infanoj = children

This is one of the most basic Esperanto endings:

• singular noun: no -j
• plural noun: add -j

Yes. That would also be correct.

Esperanto word order is fairly flexible, especially with clauses. You can put the reason first or second:

• Li diris la veron, ĉar li ne volis mensogi antaŭ la infanoj.
• Ĉar li ne volis mensogi antaŭ la infanoj, li diris la veron.

Both mean the same thing. The second version emphasizes the reason a little more.

A rough guide:

• ĉ sounds like ch in church
• aŭ sounds like a diphthong somewhat like ow in cow, but shorter and cleaner
• j sounds like English y

So approximately:

• ĉar ≈ char
• antaŭ ≈ an-tow
• infanoj ≈ in-fa-noy

Also, Esperanto spelling is very regular, so words are pronounced much more consistently than in English.