Histrio personatus larvam gerit.

You can tell from the case endings.

• histrio is the subject: it is in the nominative singular
• larvam is the direct object: it is in the accusative singular
• personatus matches histrio, so it describes the subject
• gerit is the verb: wears / carries / bears

So the structure is:

histrio = the actor
personatus = masked
larvam = a mask
gerit = wears

Because it is the direct object of gerit.

For many first-declension nouns:

• nominative singular: -a
• accusative singular: -am

So:

• larva = subject form
• larvam = object form

Since the actor is doing the wearing, and the mask is the thing being worn, Latin uses larvam.

Personatus is describing histrio. It works like an adjective here: masked or wearing a mask.

It agrees with histrio in:

• gender: masculine
• number: singular
• case: nominative

So histrio personatus means the masked actor or an actor, masked.

Because it agrees with histrio.

In Latin, adjectives must match the noun they describe in:

• gender
• number
• case

Since histrio is masculine singular nominative, personatus must also be masculine singular nominative.

If the noun were feminine, you would expect a feminine form; if plural, a plural form.

Because not all masculine Latin nouns end in -us.

Histrio is a third-declension noun, and third-declension nominatives come in many different shapes. So a masculine subject does not have to look like servus or dominus.

A learner often expects:

• masculine = -us

But Latin is much broader than that. Histrio is perfectly normal as a masculine nominative singular.

Gerit is the third-person singular present active indicative of gero, gerere.

So it means:

• he wears
• she wears
• it wears

Depending on context, gero can also mean carry, bear, conduct, or perform, but here with larvam, the natural meaning is wears.

That is a very natural question.

The sentence can feel repetitive in English, but the two parts are not doing exactly the same job:

• personatus describes the actor’s state or appearance
• larvam gerit states the action more explicitly: he is wearing a mask

So Latin can use both for emphasis, clarity, or style. In other words, one word is giving a description, and the other gives the action.

Because Latin has no articles.

So:

• histrio can mean the actor, an actor, or just actor
• larvam can mean the mask or a mask

Context tells you which English article makes the most sense.

Yes. Latin word order is much more flexible than English word order.

This sentence has a very ordinary Latin feel:

• noun + adjective: histrio personatus
• object before verb: larvam gerit
• verb at the end: very common in Latin

Latin uses endings to show grammar, so it does not rely on word order as heavily as English does. A different order could still mean the same thing, though the emphasis might change.

Yes. In Latin, larva can have other meanings, such as ghost, specter, or a frightening figure.

But in this sentence, the context makes mask the right meaning:

• histrio = actor
• gerit = wears
• so larvam is naturally understood as something an actor wears

Context is very important in Latin vocabulary.