Haec sententia iterum explicanda est.

Haec is the demonstrative this.

It is haec because it agrees with sententia, which is:

• feminine
• singular
• nominative

The demonstrative hic, haec, hoc changes form to match the noun it goes with.

So:

• hic = masculine nominative singular
• haec = feminine nominative singular
• hoc = neuter nominative singular

Since sententia is feminine singular, Latin uses haec sententia = this sentence / this opinion / this statement.

Sententia is nominative singular.

You can tell because it is the thing being described as needing explanation. In other words, it is the subject of the sentence.

The structure is:

• haec sententia = the subject
• iterum = adverb, again
• explicanda est = must be explained

So the basic skeleton is:

Haec sententia ... est
= This sentence/statement ... is

And what kind of is?
It is to be explained again, meaning must be explained again.

Explicanda is a gerundive, sometimes also called the future passive participle.

It comes from the verb explicare, meaning to explain.

Its form here is:

• feminine
• singular
• nominative

because it agrees with sententia.

So explicanda literally means something like:

• to be explained
• needing explanation
• requiring explanation

By itself, it is not the full verb of the sentence. It works together with est.

Explicanda est is a very common Latin construction called the passive periphrastic.

It is formed with:

• a gerundive
• plus a form of sum (to be)

So:

• explicanda = to be explained
• est = is

Together, they mean:

• is to be explained
• more naturally in English: must be explained or needs to be explained

So Haec sententia iterum explicanda est means literally:

This statement is to be explained again

and more natural English is:

This statement must be explained again.

Because the gerundive must agree with the noun it belongs to.

Here it belongs to sententia, which is:

• feminine
• singular
• nominative

So the gerundive also becomes:

• feminine
• singular
• nominative

If the noun were masculine, plural, or in another case, the gerundive would change too.

For example:

• hic liber explicandus est = this book must be explained
• hae sententiae explicandae sunt = these statements must be explained

Agreement is one of the key things to watch for with gerundives.

Because the subject, haec sententia, is singular.

Latin uses est for he/she/it is. Since there is one sententia, the verb is singular:

• est = is

If the subject were plural, Latin would use sunt:

• hae sententiae iterum explicandae sunt
• these statements must be explained again

Iterum is an adverb meaning again.

It modifies the verbal idea explicanda est, so the sense is:

must be explained again

It does not modify sententia. It is not saying the repeated statement; it is saying that the act of explaining happens another time.

So the meaning is:

• not this again-statement
• but this statement needs to be explained again

Yes, Latin word order is much freer than English word order.

This order is perfectly normal, but other orders are possible, such as:

• Haec sententia explicanda est iterum
• Iterum haec sententia explicanda est
• Explicanda est haec sententia iterum

The endings show the grammar, so Latin does not depend on fixed word order as much as English does.

That said, word order can affect emphasis:

• putting iterum earlier can emphasize again
• putting explicanda est earlier can emphasize the necessity

The given order is straightforward and natural.

Yes, the meaning is very close.

Both can mean:

• This statement must be explained again

But the grammar is different:

1. explicanda est

   • passive periphrastic
   • literally is to be explained
   • often feels a bit more formal or characteristically Latin

2. explicari debet

   • infinitive + debet
   • literally ought to be explained / must be explained

A learner should recognize both, but the gerundive construction is especially important because Latin uses it very often.

Yes. With the passive periphrastic, the person who has the duty is often put in the dative.

For example:

• mihi haec sententia iterum explicanda est

This means:

• I must explain this statement again
• literally, to me this statement is to be explained again

That is a very important feature of this construction:

• the thing needing action is the grammatical subject
• the person responsible can appear in the dative

So:

• haec sententia iterum explicanda est = this statement must be explained again
• mihi haec sententia iterum explicanda est = I must explain this statement again

Not necessarily.

Sententia can mean several related things, depending on context, including:

• sentence
• statement
• opinion
• view
• judgment
• sometimes even maxim

So the exact English word depends on what kind of text this is.

If this appears in a grammar or language lesson, sentence may fit well.
If it appears in a philosophical or rhetorical context, statement or opinion might be better.

The Latin grammar of the sentence does not change; only the best English translation may vary with context.

The dictionary form is the verb explico, explicare, explicavi, explicatum.

From that verb, Latin forms the gerundive:

• masculine singular nominative: explicandus
• feminine singular nominative: explicanda
• neuter singular nominative: explicandum

Here we have explicanda because it matches sententia.

So when you look up explicanda, you should think:

1. this is a gerundive
2. the base verb is explicare
3. the ending shows agreement with the noun it describes

Yes. Latin often expresses obligation by focusing on the thing that needs to be done, not first on the person doing it.

So instead of saying:

• someone must explain this statement

Latin very naturally says:

• this statement must be explained

That is why the passive periphrastic is so common. It presents the action as a necessity attached to the noun.

If needed, the responsible person can then be added in the dative:

• magistro haec sententia explicanda est
• the teacher must explain this statement

So the construction is passive in form, but it often expresses a very practical idea of duty or necessity.