Se a creche disser que o bebê está com sono, eu vou buscá-lo mais cedo.

Because after se when you are talking about a possible future situation, Portuguese normally uses the future subjunctive.

So:

• Se a creche disser... = If the daycare says...
• not Se a creche diz... in this meaning

This is a very common pattern:

• Se ele chegar cedo, saímos. = If he arrives early, we leave.
• Se chover, fico em casa. = If it rains, I’ll stay home.

The verb dizer is irregular, and its future subjunctive form is disser.

The future subjunctive is often based on the third-person plural preterite form.

For dizer:

• preterite: eles disseram
• remove -am → disser
• that gives the future subjunctive stem/form

So:

• quando eu disser
• se ele disser
• se a creche disser

This is something learners usually memorize through exposure rather than trying to build every form from scratch each time.

Creche means daycare or nursery/day nursery, especially for babies and very young children.

In Brazil, creche usually refers to a place where small children stay during the day while parents work.

So here, a creche is the daycare center caring for the baby.

Here que means that and introduces the content of what the daycare says.

• A creche disser que o bebê está com sono
• literally: the daycare says that the baby is sleepy

In English, that is often optional:

• If the daycare says the baby is sleepy...

In Portuguese, que is much more normally kept.

Estar com sono is the most natural everyday way to say to be sleepy or to feel sleepy.

Literally, it is to be with sleep, but you should learn it as a fixed expression:

• Estou com sono. = I’m sleepy.
• O bebê está com sono. = The baby is sleepy.

Portuguese does have words like sonolento or sonolenta, but for normal conversation, especially about children, estar com sono is much more common.

This has two parts:

• vou buscar = I am going to pick up / I will pick up
• -lo = him

So vou buscá-lo means I’m going to pick him up.

The lo refers back to o bebê.

In more formal or standard grammar, object pronouns can attach to the infinitive like this:

• buscar + o → buscá-lo

This is very common in written Portuguese and careful speech.

When an infinitive ending in -r takes an attached object pronoun like o / a / os / as, the -r drops.

So:

• buscar + lo → busca-lo

Then an accent is added to keep the stress in the right place:

• buscá-lo

The same thing happens with other verbs:

• ver + o → vê-lo
• fazer + o → fazê-lo
• encontrar + a → encontrá-la

So buscá-lo is the expected standard form.

Yes, in spoken Brazilian Portuguese, vou buscar ele is very common and natural.

But there is a difference in register:

• vou buscá-lo = more formal, more standard in writing
• vou buscar ele = very common in everyday spoken Brazilian Portuguese

So if you hear Brazilians speaking casually, buscar ele is completely normal.

Mais cedo means earlier.

In this sentence, it usually implies:

• earlier than usual
• sooner than planned

So eu vou buscá-lo mais cedo means:

• I’ll pick him up earlier
• or I’ll go get him sooner

Even without saying than usual, Portuguese often leaves that comparison understood from context.

Yes, it can be omitted.

Portuguese often drops subject pronouns because the verb already shows the subject:

• vou buscar already tells you it is I
• so Eu vou buscá-lo mais cedo and Vou buscá-lo mais cedo are both possible

Including eu can add:

• emphasis
• contrast
• clarity

Here it is not required, but it sounds perfectly natural.

Because the sentence begins with a se clause:

• Se a creche disser que o bebê está com sono, ...

In Portuguese, when this kind of conditional clause comes first, it is normally separated from the main clause with a comma.

So the structure is:

• If X happens, Y will happen.

That is why you get:

• Se a creche disser..., eu vou...

Literally, vou buscar is the structure ir + infinitive, which means going to do something.

In Brazilian Portuguese, this is one of the most common ways to talk about the future:

• Eu vou buscar = I’m going to pick up / I will pick up

So even though vou is present tense, the whole expression refers to a future action.

It is often more common in speech than a simple future form like buscarei.

Yes. A more formal version could be:

• Se a creche disser que o bebê está com sono, eu o buscarei mais cedo.

But this sounds more formal or written.

In everyday Brazilian Portuguese, vou buscar is much more common and natural than buscarei.

So the original sentence sounds very normal and conversational.

Grammatically, bebê can refer to either a male or female baby, but it often takes o as a masculine noun in general use.

So you may hear:

• o bebê for a baby in general
• and then people may still use ele or ela depending on the actual child

In this sentence, the pronoun -lo shows the baby is being referred to as him, or at least grammatically treated as masculine in the sentence.

If it were clearly a girl, you could say:

• Se a creche disser que a bebê está com sono, eu vou buscá-la mais cedo.

Though in real usage, many speakers still say o bebê regardless.

Yes, but it depends on the meaning.

When se refers to a real future possibility, Portuguese normally uses the future subjunctive:

• Se a creche disser... = If the daycare says...

But for general truths or repeated situations, the present tense can appear:

• Se o bebê está com sono, ele chora. = If the baby is sleepy, he cries.

So in your sentence, because it is about a future possible event, disser is the correct choice.