Puella mentum tangit.

Because puella is in the nominative singular, which is the case normally used for the subject of a sentence.

So in Puella mentum tangit:

• puella = the subject, the girl
• mentum = the direct object, the chin
• tangit = touches

A very literal breakdown is girl chin touches, but in good English we say the girl touches the chin.

Here mentum is in the accusative singular, because it is the direct object of tangit. It answers the question touches what? → the chin.

So:

• puella = nominative singular
• mentum = accusative singular
• tangit = verb

Because mentum is a neuter second-declension noun.

Many second-declension nouns work like this:

• masculine nominative singular often ends in -us
• neuter nominative singular often ends in -um

So mentum is not an unusual form at all; it is its normal dictionary form.

Also, for neuter nouns, the nominative singular and accusative singular are often the same. That is why mentum looks the same whether it is the subject or the object. In this sentence, though, it is clearly the object.

You tell from the whole sentence, not from the word by itself.

In Puella mentum tangit, puella is clearly nominative, so it is the subject. That means mentum must be the thing being touched, so it is understood as the accusative direct object.

Latin often works this way: one word alone may be ambiguous, but the sentence makes the role clear.

Tangit is the third-person singular present active indicative of tangere, meaning to touch.

That tells you:

• third person = he/she/it
• singular = one person or thing
• present = touches or is touching
• active = the subject is doing the action

So tangit can mean:

• he touches
• she touches
• it touches
• sometimes in context, is touching

Here, because the subject is puella, it means the girl touches.

Because Latin has no articles. It does not have separate words that exactly match English the, a, or an.

So puella can mean:

• girl
• a girl
• the girl

And mentum can mean:

• chin
• a chin
• the chin

The context or the translation determines which English article sounds best.

Not as much as in English. Latin word order is much more flexible because the endings show the grammatical roles.

So all of these could express basically the same idea:

• Puella mentum tangit
• Mentum puella tangit
• Tangit puella mentum

The sentence you have, Puella mentum tangit, is a very normal Latin order, with the verb placed at the end. Verb-final order is especially common in Latin prose.

Even when the order changes, the endings still show that puella is the subject and mentum is the object.

Because the verb ending already includes the idea of he/she/it.

The ending -it in tangit tells you the verb is third-person singular. So Latin does not need to add a separate subject pronoun unless it wants extra emphasis or clarity.

That means:

• tangit by itself can mean he touches, she touches, or it touches
• puella tangit makes clear that the she is the girl

English usually needs the pronoun, but Latin often does not.

Yes, it could, depending on context.

Latin often leaves some things unstated when they are obvious from the situation. With body parts, English often uses her, his, or their, even when Latin does not explicitly say it.

So Puella mentum tangit might mean:

• the girl touches the chin
• the girl touches her chin

If Latin wanted to make her own chin especially explicit, it could say Puella mentum suum tangit.

No. In this tense, the verb agrees with the subject in person and number, not in gender.

So:

• Puella mentum tangit = the girl touches the chin
• Puer mentum tangit = the boy touches the chin

The verb stays tangit in both sentences because both subjects are third-person singular.

A learner will usually meet them like this:

• puella, puellae = girl
• mentum, menti = chin
• tango, tangere = touch

More fully, you may see:

• puella, puellae, f. = first-declension feminine noun
• mentum, menti, n. = second-declension neuter noun
• tango, tangere, tetigi, tactum = verb meaning touch

Those dictionary forms help you identify how each word changes in different sentences.