La barbacoa empieza al mediodía.

In Spanish, it is very common to use the definite article with nouns where English might leave it out. La barbacoa means the barbecue / the BBQ.

In context, it sounds natural because it refers to a specific event everyone already knows about. Spanish often uses articles more than English does.

Barbacoa can refer to:

• the barbecue as an event or meal
• the grill / barbecue equipment
• sometimes the food cooked on a barbecue

In this sentence, La barbacoa empieza..., it most naturally means the barbecue gathering/event starts at noon.

Empezar is the infinitive, meaning to start.
Empieza is the third-person singular present tense form, used with la barbacoa:

• empezar = to start
• la barbacoa empieza = the barbecue starts

So the verb changes to match the subject.

Both empezar and comenzar mean to begin / to start. In this sentence, either could work:

• La barbacoa empieza al mediodía.
• La barbacoa comienza al mediodía.

Empezar is very common and natural in everyday speech. Comenzar can sound a little more formal, though both are perfectly normal.

Yes. Empezar is a stem-changing verb in the present tense: e → ie.

So:

• yo empiezo
• tú empiezas
• él / ella / usted empieza

But:

• nosotros empezamos
• vosotros empezáis
• ellos / ellas / ustedes empiezan

That is why you see empieza, not empeza.

Because al is the contraction of a + el:

• a el → al

The noun is el mediodía (midday / noon), so:

• a + el mediodía → al mediodía

This contraction is required in standard Spanish.

Mediodía means midday or noon.

In most everyday contexts, al mediodía means at noon or around lunchtime, depending on the situation. In Spain, people may sometimes use it a bit more flexibly than the exact English 12:00 sharp, but often it does simply mean noon.

Normally, in this expression, Spanish uses al mediodía. That is the standard and natural form.

A learner should treat al mediodía as the normal expression for at noon.

Because la barbacoa is the subject of the sentence, not part of a time expression.

The structure is:

• La barbacoa = subject
• empieza = verb
• al mediodía = time expression

So literally it is:

• The barbecue starts at noon

Spanish does not need any extra word before la barbacoa here.

Yes. Spanish word order is more flexible than English. You could also say:

• La barbacoa empieza al mediodía.
• Al mediodía empieza la barbacoa.

Both are correct. The second version emphasizes the time a bit more. The first is the most neutral and straightforward.

A rough pronunciation guide:

• barbacoa ≈ bar-ba-KO-a
• mediodía ≈ meh-dyo-DEE-a

A few useful points for Spain Spanish:

• b and v are pronounced the same or very similarly
• coa in barbacoa is three vowels in sequence, not one English-style sound
• the written accent in mediodía shows the stress falls on -dí-

The accent mark shows where the stress goes: me-dio-DÍ-a.

Without the accent, the stress rules would suggest a different pronunciation. So the accent is necessary both for correct pronunciation and for correct spelling.

It depends on what you want to say.

• La barbacoa empieza al mediodía = The barbecue starts at noon
• La barbacoa es al mediodía = The barbecue is at noon

The second one is understandable and can work in some contexts, but empieza al mediodía is more precise because it tells you the starting time. If you are talking about the event schedule, empieza is usually the better choice.

Sometimes people might say other things depending on what they mean, for example:

• la parrillada = a grilled meal / barbecue meal
• la comida = the meal / lunch
• la fiesta = the party

But la barbacoa is a very common and natural word in Spain for a barbecue event.