La media jornada termina antes de la jornada completa.

Because jornada is a feminine noun, and the adjective has to agree with it.

• jornada → feminine singular
• so the adjective is media, not medio

Compare:

• medio día = half a day / noon (día is masculine)
• media jornada = a half-day shift / part-time schedule (jornada is feminine)

This is simple adjective agreement.

In this sentence, jornada means a workday, work shift, or working schedule.

In Spain, it is very commonly used when talking about employment:

• jornada completa = full-time schedule / full workday
• media jornada = half-day schedule / part-time schedule

So jornada is not just the abstract idea of a day. In work-related contexts, it usually refers to the hours worked.

Not always in a strict mathematical sense.

In real Spanish usage, especially in Spain, media jornada often means part-time work. It may literally be about half the usual daily hours, but it can also be used more generally for a reduced schedule.

So depending on context, media jornada can suggest:

• a half-day shift
• a part-time job
• a reduced working schedule

A learner should understand that it is often a set work expression, not just a perfectly literal fraction.

Because both noun phrases need their own article.

• la media jornada = the half-day schedule / the part-time shift
• la jornada completa = the full-day schedule / the full-time shift

Spanish uses the definite article very naturally in general statements, often more than English does. Here it is referring to these categories in a general sense, not necessarily to one specific shift already mentioned.

So the sentence is talking about the two types of schedule as concepts:

• the part-time shift
• the full-time shift

Because the subject is La media jornada, which is singular.

Breakdown:

• La media jornada = singular subject
• termina = third person singular of terminar

If the subject were plural, the verb would also be plural:

• Las medias jornadas terminan antes...

So this is just normal subject-verb agreement.

The present tense is used here to express a general fact or usual situation.

Spanish, like English, often uses the present for things that are generally true:

• La media jornada termina antes...
• El agua hierve a 100 grados.
• Los bancos abren a las nueve.

So termina does not have to mean it is happening right now at this moment. It can simply mean this is what normally happens.

Because antes de is used before a noun or noun phrase, while antes que is used before a clause with a verb.

Here, what follows is a noun phrase:

• la jornada completa

So Spanish uses:

• antes de la jornada completa

If you used a full clause, then antes que would be possible:

• La media jornada termina antes que termine la jornada completa.

That version is grammatical, but longer and less natural here. The original sentence is more concise.

Yes, very often.

• La media jornada termina antes de la jornada completa.
• La media jornada acaba antes de la jornada completa.

Both are natural and understandable.

That said:

• terminar is often a bit more neutral or formal
• acabar is very common in everyday speech

In many contexts, there is little practical difference between them.

They are opposite work-schedule ideas.

• media jornada = part-time / half-day schedule
• jornada completa = full-time / full-day schedule

In employment contexts in Spain:

• trabajar a media jornada = to work part-time
• trabajar a jornada completa = to work full-time

So this sentence contrasts the two schedules by saying one ends earlier than the other.

Because Spanish often avoids repetition when the meaning is already clear.

The sentence says:

• La media jornada termina antes de la jornada completa.

Literally, the comparison is compact. Spanish does not need to say something like:

• La media jornada termina antes de que termine la jornada completa

unless the speaker wants to make the clause more explicit.

This shorter structure is very common and natural. Spanish often prefers the more economical version when there is no ambiguity.

It can mean both, depending on context.

In many job-related situations in Spain, jornada completa is commonly understood as full-time employment or a full-time schedule, not just one specific day.

For example:

• Busco trabajo de jornada completa. = I’m looking for a full-time job.
• Tiene jornada completa. = He/She works full-time.

So in your sentence, it could refer to:

• a full-day shift in comparison with a half-day shift, or
• more generally, the full-time schedule as a category

Context decides which nuance is strongest.

Yes. Here are some natural alternatives:

• La jornada completa termina después de la media jornada.
• La media jornada acaba antes que la jornada completa.
• La media jornada finaliza antes que la jornada completa.

All of these keep the same basic idea.

The original sentence is good because it is:

• clear
• natural
• simple
• very typical of work-related Spanish

So it is a useful model sentence for learners.