Si el envase está vacío, lo reutilizo para guardar arroz.

Yes. Si here means if and introduces a condition:

• Si el envase está vacío... = If the container is empty...

Be careful not to confuse this with sí (with an accent), which means yes or himself/itself in some contexts. In this sentence, it is the conjunction si = if.

Envase is a masculine noun, so it takes el.

• el envase = the container / packaging / receptacle

In this sentence, envase suggests some kind of container that can be reused, such as a jar, tub, or plastic container. It is a fairly general word.

Because it is masculine singular:

• el envase
• vacío
• lo

all agree with that masculine singular noun.

Spanish usually uses estar for a current state or condition, and ser for identity, essence, or defining characteristics.

So:

• está vacío = it is empty right now, as a state
• es vacío would sound odd here, because emptiness is not being presented as the container’s essential nature

A container is not inherently empty; it is empty at this moment. That is why estar is the natural choice.

Vacío has a written accent because the stress falls on the í:

• va-CÍ-o

The accent also helps show that í and o are pronounced in separate syllables, not merged together. So it is:

• va-cí-o

not one smoother syllable at the end.

Lo is a direct object pronoun meaning it. It refers back to el envase.

So:

• el envase = the container
• lo reutilizo = I reuse it

Spanish often replaces a repeated noun with a pronoun, just as English does.

Full idea:

• Si el envase está vacío, lo reutilizo...
• If the container is empty, I reuse it...

Because envase is masculine singular, the pronoun is lo.

Because envase is the direct object of reutilizo.

• Reutilizar algo = to reuse something

So the thing being reused is a direct object:

• reutilizo el envase
• lo reutilizo

In standard Spanish, direct masculine singular objects take lo, not le.

Reutilizo is the first person singular present indicative of reutilizar:

• yo reutilizo = I reuse / I reuse it

It ends in -o, which is typical for yo in the present tense.

Examples:

• reutilizo = I reuse
• reutilizas = you reuse
• reutiliza = he/she/it reuses

In this sentence, it expresses a habitual action: whenever the container is empty, I reuse it.

Spanish often uses the present tense in both clauses for general truths, habits, or repeated situations.

• Si el envase está vacío, lo reutilizo...

This means something like:

• If the container is empty, I reuse it
• Whenever the container is empty, I reuse it

It is not talking about one specific future event. It sounds habitual or routine.

If you wanted a future meaning, Spanish often still uses the present after si:

• Si el envase está vacío mañana, lo reutilizaré
• If the container is empty tomorrow, I’ll reuse it

Notice that after si, Spanish does not normally use the future tense in this kind of sentence.

Para means for or in order to, and guardar means to keep / to store.

So:

• para guardar arroz = to store rice / for storing rice

It explains the purpose of reusing the container.

So the structure is:

• reutilizo [something] para + infinitive
• I reuse [something] to + verb

Examples:

• Lo reutilizo para guardar arroz = I reuse it to store rice
• Lo uso para guardar azúcar = I use it to store sugar

Because arroz here is being used as a mass noun in a general sense, like rice in English.

• guardar arroz = store rice
• guardar el arroz = store the rice

With el arroz, you would usually be referring to a specific rice already known from the context. Without the article, it means rice in general.

Yes. Guardar is a very common verb with a range of meanings, including:

• to keep
• to store
• to put away
• to save

In this sentence, store is probably the best translation, because you are putting rice in a container. But keep rice in it could also fit the idea.

The comma separates the if-clause from the main clause:

• Si el envase está vacío, lo reutilizo...

This is very common in Spanish, especially when the conditional clause comes first.

It helps the sentence read clearly:

• condition first: If the container is empty,
• result next: I reuse it to store rice

Not naturally in this version.

• Si el envase está vacío, reutilizo para guardar arroz is incomplete, because reutilizar normally needs an object: reuse what?

You need either:

• Si el envase está vacío, lo reutilizo... or
• Si el envase está vacío, reutilizo el envase...

Since repeating el envase sounds less natural, Spanish prefers the pronoun lo.

Both are correct, but they feel slightly different.

• lo reutilizo = I reuse it
• vuelvo a usarlo = I use it again

Reutilizar sounds a bit more formal or precise. Volver a usar is very common in everyday speech and may sound more conversational.

So a native speaker might also say:

• Si el envase está vacío, vuelvo a usarlo para guardar arroz.

Both are good Spanish.

A Spain pronunciation would roughly sound like this:

• Si el em-BA-se es-TA va-SEE-o, lo re-u-ti-LEE-tho pa-ra guar-DAR a-RROTH

A few Spain-specific features:

• z in reutilizo is pronounced like th in thin in most of Spain
• c before e/i would also have that th sound in most of Spain
• rr in arroz is a rolled or trilled r

Also note:

• vacío has stress on cí
• reutilizo has stress on li

Yes, a little. Spanish word order is flexible, though the original sentence is very natural.

Original:

• Si el envase está vacío, lo reutilizo para guardar arroz.

Possible variation:

• Lo reutilizo para guardar arroz si el envase está vacío.

That version is grammatically correct, but the original sounds more natural if you want to emphasize the condition first.

Starting with Si... is very common when the condition is the main setup for the sentence.