La niña quería otra tarrina con sirope de chocolate, pero su madre dijo que una era suficiente.

Quería is the imperfect of querer, and here it describes an ongoing desire or wish in the background: the girl wanted another tub.

If you said quiso, that would be the preterite, which often sounds more like a completed event: she tried to / she wanted to and that moment is viewed as finished.

So in this sentence:

• La niña quería otra tarrina... = The girl wanted another tub...
• it sets the scene and describes what she wanted at that moment.

This is very natural in storytelling:

• quería = background desire
• dijo = the specific action that happened next

Tarrina usually means a small tub, cup, or container, especially for food.

In this sentence, it likely refers to a tub/cup of ice cream or dessert. In Spain, tarrina is commonly used for things like:

• an ice cream tub
• a small dessert container
• a serving in a little plastic or cardboard pot

So otra tarrina con sirope de chocolate means something like:

• another tub/cup with chocolate syrup
• or more naturally in context, another ice cream cup with chocolate syrup

In Spanish, otro / otra usually means another by itself, so you normally do not add una before it.

So:

• otra tarrina = another tub
• not una otra tarrina

This is different from English, where another historically comes from an + other, but in modern Spanish otra already does that job on its own.

Compare:

• Quiero otra. = I want another one.
• Compró otro libro. = He bought another book.

Because tarrina is a feminine singular noun.

Adjectives and determiners like otro / otra must agree with the noun they describe:

• otro libro = another book
• otra tarrina = another tub

Here:

• tarrina ends in -a and is feminine
• so the correct form is otra

Con sirope de chocolate means with chocolate syrup.

Breakdown:

• con = with
• sirope = syrup
• de chocolate = of chocolate / chocolate

In Spanish, de + noun is often used like an English noun modifier:

• helado de vainilla = vanilla ice cream
• tarta de queso = cheesecake
• sirope de chocolate = chocolate syrup

You usually do not need an article here, because chocolate is being used as a material/type description, not referring to a specific chocolate.

In Spain, sirope is very common for dessert syrup, especially toppings like chocolate, strawberry, or caramel syrup.

• sirope de chocolate = chocolate syrup

Jarabe also means syrup, but it is often associated more with:

• medicine syrup
• a more general liquid syrup
• sometimes formal or technical contexts

So for ice cream or dessert toppings in Spain, sirope sounds the most natural.

Yes. Su can mean:

• his
• her
• its
• their
• your (formal singular)
• your (plural in many Latin American varieties)

In this sentence, context tells us that su madre means her mother, referring to la niña.

Spanish uses su much more broadly than English uses his/her/their, so context is very important.

If needed, Spanish can clarify:

• la madre de la niña = the girl’s mother
• su madre de ella = her mother (more emphatic/clarifying, less neutral in many contexts)

But here, su madre is perfectly normal and clear.

Because Spanish often avoids repeating a noun when it is already clear from context.

Here, una stands in for una tarrina:

• una era suficiente = one was enough

This works like English:

• She wanted another cup, but her mother said one was enough.

So una here is basically one, referring back to tarrina.

Because tarrina is feminine, Spanish uses:

• una = one (feminine) not
• uno = one (masculine)

Compare:

• un libro es suficiente → uno es suficiente
• una tarrina es suficiente → una es suficiente

Here era suficiente describes a state or assessment: one was enough.

Spanish often uses the imperfect for descriptions, states, and circumstances in the past. The mother’s statement is presented as a judgment about the situation, not as a completed event in itself.

So:

• dijo que una era suficiente = she said that one was enough

Using fue suficiente would sound more like turned out to be enough or was enough as a completed fact/result, which is less natural in this context.

This contrast is common:

• dijo que estaba cansada = she said she was tired
• dijo que era suficiente = she said it was enough

The main verb dijo is a completed action, but the clause after que can still use the imperfect if it describes a state.

Because suficiente is an adjective that does not change for gender in the singular.

So you get:

• un helado suficiente (not very natural, but grammatically possible)
• una tarrina suficiente
• uno es suficiente
• una es suficiente

The only change is in the plural:

• suficiente = singular
• suficientes = plural

Examples:

• Uno es suficiente. = One is enough.
• Dos son suficientes. = Two are enough.

Here que means that and introduces a subordinate clause.

• dijo que... = said that...

So:

• su madre dijo que una era suficiente = her mother said that one was enough

In English, that is often omitted:

• Her mother said one was enough.

In Spanish, que is normally required after verbs like:

• decir = to say
• pensar = to think
• creer = to believe

Examples:

• Dijo que no. = She said no.
• Creo que viene. = I think he’s coming.
• Pensó que era tarde. = He thought it was late.

Yes. The original sentence is natural, but Spanish offers other possibilities depending on style.

For example:

• La niña quería otra tarrina con sirope de chocolate, pero su madre dijo que con una bastaba.

  • literally: ...but her mother said one was enough / one would do

• La niña quería otra tarrina con sirope de chocolate, pero su madre dijo que una ya era suficiente.

  • ya adds the idea of already

• La niña quería otra tarrina..., pero su madre le dijo que una era suficiente.

  • adding le makes it explicit that the mother said it to her

The original sentence is completely correct and natural; these are just stylistic variations.