Puella chartam sinistra tenet et dextra scribit.

Because chartam is the accusative singular of charta. In this sentence, it is the direct object of tenet: the girl is holding the paper.

• charta = paper, sheet
• chartam = paper/sheet as the thing being held

A native English speaker often expects word order to show the object, but in Latin the case ending does that job.

Because they are not direct objects. Here they are in the ablative singular, meaning with the left hand and with the right hand.

So:

• sinistra = with the left hand
• dextra = with the right hand

Latin often leaves out the noun manu (hand) when it is obvious. So the fuller version would be something like:

• sinistra manu tenet et dextra manu scribit

But Latin commonly shortens this to just sinistra and dextra.

Yes. This is a very common kind of omission in Latin. The adjective can stand by itself when the noun is easy to supply from context.

Here:

• sinistra = with the left hand
• dextra = with the right hand

This is natural Latin, not an incomplete sentence. English usually needs to spell out hand, but Latin often does not.

Because it does not have to. Scribit simply means she writes or is writing. The sentence focuses on how she writes—with her right hand—not on what she writes.

Latin can leave the object unstated when it is unknown, unimportant, or obvious from context.

So this sentence means something like:

• The girl holds the paper with her left hand and writes with her right.

It does not need to say what she is writing.

Because the verb ending already tells you the subject.

• tenet = she/he/it holds
• scribit = she/he/it writes

Since puella is present, we know the subject is the girl, so English translates it as she in the second verb if needed. Latin does not need to repeat a pronoun.

Latin word order is much freer than English word order because endings show the grammatical relationships.

This means Latin can arrange words for:

• emphasis
• style
• rhythm
• clarity

In chartam sinistra tenet, the object chartam comes before the verb, and sinistra is placed near tenet to show the manner/instrument. English depends more heavily on order, but Latin depends more on inflection.

Et simply means and, joining the two actions:

• tenet = holds
• scribit = writes

Latin sometimes can connect ideas without an explicit and, but here et is the normal, straightforward way to link the two verbs.

Puella is nominative singular because it is the subject of both verbs.

• puella = the girl
• she is the one who holds
• she is the one who writes

A learner often notices that Latin does not need to repeat the subject before the second verb. Puella naturally applies to both tenet and scribit.

They are originally adjectives, meaning left and right, but here they are being used substantively, with an understood noun.

In other words:

• sinistra = the left hand
• dextra = the right hand

More precisely, because they are in the ablative, they mean:

• with the left hand
• with the right hand

So they are adjectives functioning almost like nouns because manu is omitted.

They are both present tense, third person singular, active voice.

• tenet = she holds / she is holding
• scribit = she writes / she is writing

Latin present tense can often be translated in more than one way in English, depending on context:

• she holds / she is holding
• she writes / she is writing

In this sentence, English often prefers the progressive sense: is holding and is writing.

Not in this sentence. Here the context and the grammar strongly point to the ablative of means/instrument:

• sinistra tenet = holds with the left hand
• dextra scribit = writes with the right hand

Because the actions are things normally done with the hands, that interpretation is the natural one. Also, the omitted manu is a very common Latin pattern.

Latin has no definite article and no indefinite article. So there is no separate word for the or a/an.

That means:

• puella can mean girl or the girl
• chartam can mean a paper, paper, or the paper

English has to choose the most natural option from context. In this sentence, the girl and the paper are good translations.