Las horas extra empiezan después de la jornada laboral.

Spanish uses articles more often than English does.

In this sentence, las horas extra is the subject, so las sounds natural and expected. English often leaves the article out in similar cases, but Spanish usually keeps it.

Compare:

• Las horas extra empiezan... = Overtime starts...
• La jornada laboral termina a las seis. = The working day ends at six.

So even if English has no article, Spanish often does.

Because extra is commonly used as an invariable adjective in Spanish. That means its form does not change for singular/plural or masculine/feminine in this kind of expression.

So you get:

• una hora extra
• dos horas extra

A more formal alternative is horas extraordinarias, where the adjective does agree:

• una hora extraordinaria
• dos horas extraordinarias

In everyday Spanish in Spain, horas extra is very common.

Empiezan is the 3rd person plural present indicative of empezar.

The infinitive is empezar = to begin / to start.

Here is the present tense:

• yo empiezo
• tú empiezas
• él/ella empieza
• nosotros empezamos
• vosotros empezáis
• ellos/ellas empiezan

It is a stem-changing verb: e → ie in most forms.

The subject is las horas extra, which is plural, so the verb must also be plural:

• Las horas extra empiezan...

This happens because empezar is a stem-changing verb.

In the present tense, the e in the stem changes to ie in all forms except nosotros and vosotros.

So:

• empiezo
• empiezas
• empieza
• empezamos
• empezáis
• empiezan

This is very common in Spanish. Other verbs do similar things, such as:

• pensar → pienso
• cerrar → cierra
• comenzar → comienza

Because when después is followed by a noun, Spanish normally uses de.

So:

• después de la jornada laboral = after the working day

You can think of después de as a fixed pattern before a noun phrase.

More examples:

• después de clase
• después del trabajo
• después de la cena

You may see después on its own when nothing follows it or when the rest is understood:

• Primero trabajo y después descanso.

Because jornada is a feminine noun, so it takes la, not el.

• la jornada
• de la jornada

Del is only a contraction of de + el:

• de + el = del

Since this noun is feminine, there is no contraction:

• de la jornada laboral

Jornada laboral is a set phrase meaning working day, workday, or working hours/shift, depending on context.

It is a bit more specific and formal than just trabajo.

• trabajo = work / job
• jornada laboral = the period of time you work in a day, your working day, or your scheduled work period

So in this sentence, it means that the overtime begins after the normal working day or regular working hours end.

In Spanish, most adjectives usually come after the noun, especially when they classify or describe the type of thing.

So:

• jornada laboral = working day
• horario laboral = work schedule
• accidente laboral = work-related accident

Here laboral is a classifying adjective: it tells you what kind of jornada it is. That makes the post-noun position the normal one.

Yes. Horas extra is very common and natural in Spain.

You will also hear the more formal or legal expression:

• horas extraordinarias

Both refer to overtime, but:

• horas extra = more everyday
• horas extraordinarias = more formal, administrative, or legal

A useful phrase is:

• hacer horas extra = to do overtime / to work overtime

Spanish commonly expresses this idea as extra hours, so the plural is very natural:

• las horas extra

If you mean one specific extra hour, you can use the singular:

• una hora extra

Spanish can also use other expressions depending on context, but horas extra is the most normal everyday way to talk about overtime as a concept.

The h in Spanish is silent.

So horas is pronounced roughly like oras.

A simple pronunciation guide:

• horas → OH-ras
• extra → EKS-tra
• empiezan → em-PYE-than in much of Spain, or em-PYE-san in Latin American pronunciation
• jornada → jor-NA-da
• laboral → la-bo-RAL

For Spain specifically, remember that z in empiezan is usually pronounced like the th in think.

Yes. Comienzan and empiezan both mean begin or start, and both would work here.

• Las horas extra empiezan después de la jornada laboral.
• Las horas extra comienzan después de la jornada laboral.

In many everyday contexts, empezar is a little more common in casual speech, while comenzar can sound slightly more formal or neutral. But both are correct.