Lucia autem dicit aliud participium ad futurum pertinere, quia rem mox faciendam significat.

In Latin, autem is a postpositive word, which means it normally comes after the first word or phrase of its clause, not before it.

So:

• Lucia autem dicit = Lucia, however, says...

Even though we translate autem as however, moreover, or but, Latin usually places it in the second slot.

This is a very common Latin construction: accusative + infinitive after verbs of saying, thinking, knowing, and perceiving.

Here:

• dicit = she says
• aliud participium = the subject of the infinitive, put in the accusative
• pertinere = to pertain

So Lucia dicit aliud participium ad futurum pertinere literally means:

• Lucia says another participle to pertain to the future

More natural English:

• Lucia says that another participle pertains to the future.

Latin often uses this infinitive construction where English uses that + a finite verb.

Aliud participium is neuter singular accusative.

Why accusative? Because in an accusative-and-infinitive construction, the logical subject of the infinitive is put in the accusative.

So in:

• dicit aliud participium ad futurum pertinere

the phrase aliud participium is the thing that is said to pertain to the future.

Both words are neuter singular accusative:

• aliud = another / a different
• participium = participle

Aliud is the neuter singular form of alius, meaning:

• another
• a different
• some other

Because it modifies participium, it must match it in gender, number, and case:

• participium is neuter singular
• therefore aliud is also neuter singular

So aliud participium means:

• another participle
• a different participle

Pertinere ad means to pertain to, to relate to, or to belong to.

So:

• ad futurum = to the future

Here futurum is neuter singular accusative, used almost like a noun: the future.

So the phrase means:

• to pertain to the future

You could think of an understood noun like tempus in the background, but Latin often does not need to state it explicitly.

Pertinere literally means to extend to, and in many contexts it means:

• to pertain to
• to relate to
• to belong to

So here:

• aliud participium ad futurum pertinere
• another participle pertains to the future
• or another participle belongs to the future

This is describing the grammatical function of that participle.

Quia means because and introduces a reason.

So:

• quia rem mox faciendam significat
• because it indicates a thing soon to be done

The verb after quia is a normal finite verb:

• significat = it signifies / indicates

This clause explains why Lucia says that the participle belongs to the future.

This phrase is the object of significat.

Break it down:

• rem = thing, accusative singular of res
• mox = soon
• faciendam = to be done, feminine singular accusative, agreeing with rem

So the whole phrase means:

• a thing soon to be done

Since significat takes a direct object, rem mox faciendam is what is being signified.

Faciendam is a gerundive of facere.

More specifically, it is:

• feminine
• singular
• accusative

It agrees with rem.

The gerundive often has the sense of:

• to be done
• needing to be done
• destined to be done

So:

• rem faciendam = a thing to be done

With mox:

• rem mox faciendam = a thing soon to be done

In this sentence, that future-oriented sense helps explain why the participle is said to belong to the future.

Because res is the nominative form, while rem is the accusative singular.

Here the word is the direct object of significat, so Latin uses the accusative:

• significat rem = it signifies a thing

That is why we get rem mox faciendam, not res mox facienda.

It can suggest that idea, because the gerundive often carries a sense of necessity or suitability. But in many contexts, especially when translated smoothly into English, it is enough to say:

• to be done
• going to be done
• about to be done

Here the important point is that the action lies in the future relative to the participle being discussed. So the phrase emphasizes futurity more than strong obligation.

The subject is understood from the context: it is the participle being discussed.

So the sense is:

• because it signifies a thing soon to be done

Here it refers to aliud participium.

Latin often leaves a subject unexpressed when it is clear from the context or from the verb ending.

Yes. Participium means participle in the grammatical sense.

So the sentence is talking about Latin grammar: Lucia says that one participle belongs to the future because it expresses something that is going to be done soon.

This is the kind of explanation you might see in a grammar discussion about Latin participles.

A useful way to divide it is:

• Lucia autem dicit = main verb: Lucia, however, says
• aliud participium ad futurum pertinere = indirect statement: that another participle pertains to the future
• quia rem mox faciendam significat = reason clause: because it signifies a thing soon to be done

So the sentence has:

1. a main clause,
2. an accusative-and-infinitive construction after dicit,
3. a quia clause giving the reason.