Fine li konfesis, ke la kulpo vere estis lia.

Fine means finally, in the end, or at last.

In this sentence, it shows that the confession happened after some delay, hesitation, or previous denial.

• Fine li konfesis... = Finally he confessed...

It is an adverb, and putting it at the beginning is very natural.

In Esperanto, commas are commonly used to separate a main clause from a subordinate clause.

Here:

• Fine li konfesis = the main clause
• ke la kulpo vere estis lia = the subordinate clause

So the comma before ke is normal Esperanto punctuation.

Ke means that and introduces a content clause.

So:

• li konfesis, ke... = he confessed that...

It works much like English that in sentences such as:

• He said that...
• She knew that...
• They admitted that...

In Esperanto, ke is very common after verbs of saying, thinking, knowing, believing, confessing, and so on.

La kulpo means the guilt, the fault, or the blame.

The article la is used because this is a specific guilt/fault being talked about, not guilt in general. The sentence is about a particular matter already understood from context.

So:

• kulpo = guilt/fault in a general sense
• la kulpo = the guilt / the fault / the blame in this situation

Kulpo can mean fault, blame, or guilt, depending on context.

In this sentence, it means something like:

• the fault was really his
• the blame really belonged to him
• he really was the one at fault

A native English speaker should notice that Esperanto kulpo can cover a range that English sometimes splits into different words.

Estis is the past tense of esti (to be).

Since the main verb is also in the past:

• li konfesis = he confessed

the sentence reports something in the past, so estis is the natural choice:

• ke la kulpo vere estis lia = that the fault really was his

In some contexts, Esperanto can use present tense inside a ke-clause if the speaker wants to present something as still true now, but here the straightforward past tense is the most natural.

Lia is the possessive form meaning his.

In Esperanto, possessive words like mia, via, lia, ŝia, nia, ilia can be used either:

1. before a noun

   • lia kulpo = his fault

2. by themselves

   • la kulpo estis lia = the fault was his

So here lia stands alone, just like English his in it was his.

This is a very important Esperanto point.

Sia refers to the subject of its own clause.

In the subordinate clause here:

• ke la kulpo vere estis lia

the grammatical subject is la kulpo, not li.

So sia would refer back to la kulpo, which would make no sense here. That is why Esperanto uses lia.

Compare:

• Li konfesis sian kulpon.
  = He confessed his own fault.
  Here sian refers to li, because li is the subject of that clause.

But in:

• Li konfesis, ke la kulpo estis lia.
  the clause after ke has its own structure, and its subject is la kulpo, so sia cannot refer to li there.

Yes. Both are possible.

• Fine li konfesis
• Li fine konfesis

Both mean essentially He finally confessed.

Putting fine first gives it a little more emphasis, like Finally, he confessed. Esperanto word order is fairly flexible, especially with adverbs.

Vere means really, truly, or actually.

It emphasizes that the guilt genuinely belonged to him:

• la kulpo vere estis lia = the fault really was his

Without vere, the sentence would still be correct:

• Fine li konfesis, ke la kulpo estis lia.

Adding vere gives extra emphasis.

Yes. Esperanto allows some flexibility in adverb placement.

For example, these are all possible:

• ke la kulpo vere estis lia
• ke vere la kulpo estis lia
• ke la kulpo estis vere lia

They are very similar in meaning, though the emphasis shifts slightly.

The original version sounds natural and clear.

It behaves like a possessive adjective/pronoun form, but here it is being used without a noun, so in English terms it feels more like a pronoun:

• lia kulpo = his fault
• la kulpo estis lia = the fault was his

In Esperanto grammar, these possessive forms keep the same shape whether or not the noun is stated.

Grammatically, you might understand it, but it is not the normal or best way here.

Esperanto strongly prefers the possessive form:

• la kulpo estis lia

Using de li would usually sound less natural for simple possession. De is more often used for of, source, authorship, or other relationships, not where a plain possessive works better.

So lia is the correct and idiomatic choice here.