El bombero llegó pronto.

In Spanish, it is very common to use the definite article with a noun when talking about a specific person already understood in context.

• el bombero = the firefighter
• bombero = firefighter / a firefighter, depending on context

So El bombero llegó pronto sounds like The firefighter arrived early/soon.

You can sometimes omit the article, but not in this sentence if you mean a specific firefighter as the subject.

By default, bombero is the masculine form.

• el bombero = the male firefighter
• la bombera = the female firefighter

In some contexts, the masculine form can also be used in a general or mixed sense, but in a simple sentence like this, el bombero would normally be understood as masculine.

Llegó is the pretérito form, used for a completed action in the past.

• llegó = he arrived / she arrived / it arrived

This tense presents the arrival as a finished event.

Compare:

• llegó = arrived
• llegaba = was arriving / used to arrive
• ha llegado = has arrived

In this sentence, llegó is the most straightforward way to say that the firefighter arrived.

The accent mark shows both pronunciation and verb form.

• llego = I arrive
• llegó = he/she arrived

So the accent is important because it changes the meaning.

Without the accent, it would be present tense first person singular. With the accent, it is the preterite third person singular.

Spanish often leaves out subject pronouns because the verb ending already tells you who the subject is.

In llegó, the ending tells you it is:

• he arrived
• she arrived
• it arrived
• or you (formal) arrived

Here, the noun El bombero makes it clear who the subject is, so there is no need to add él.

Here pronto is an adverb meaning something like:

• early
• soon
• quickly, depending on context

In El bombero llegó pronto, the most natural meaning is usually early or soon.

It describes when the firefighter arrived, not how he arrived.

In Spanish, adverbs like pronto often come after the verb, especially in simple statements.

So:

• llegó pronto = arrived early / arrived soon

That is the normal, natural order here.

You may sometimes see adverbs in other positions for emphasis, but llegó pronto is the standard structure.

In most of Spain, ll is usually pronounced like the y in yes.

So llegó sounds roughly like:

• ye-GO

The stress is on the second syllable because of the accent mark: lle-GÓ.

A broad approximation of the whole sentence in Spain would be:

• el bom-BE-ro ye-GO PRON-to

Here it is an adverb because it modifies the verb llegó.

It tells us more about the action of arriving.

• adjective: describes a noun
• adverb: describes a verb, adjective, or another adverb

In this sentence, pronto describes when the firefighter arrived, so it is an adverb.

Yes. Temprano is also very common and often clearer if you specifically mean early.

• llegó pronto = arrived soon / early
• llegó temprano = arrived early

So both are possible, but temprano focuses more directly on earliness, while pronto can be a bit broader depending on context.

Yes, Spanish allows more flexibility in word order than English.

You could also say:

• Llegó pronto el bombero.

This can sound more literary, contextual, or emphatic, depending on the situation. But the basic, neutral order is:

• El bombero llegó pronto.

So the original sentence is the most standard way to say it.