Antaŭ la venonta semajno mi devas decidi, ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo.

Antaŭ la venonta semajno means before next week or by next week.

Here antaŭ means before, so the speaker is giving a deadline: the decision must be made before the next week begins, or by that time.

By contrast, en la venonta semajno would mean in the coming week / during next week, which is a different idea. That would place the action inside that week, not before it.

So:

• antaŭ la venonta semajno = before next week / by next week
• en la venonta semajno = in next week / during the coming week

Both can often be translated as next week, but they are not always felt in exactly the same way.

• venonta literally means coming or about to come
• sekva means following or next in sequence

So la venonta semajno is very naturally the coming week.

In many everyday contexts, both are possible, but venonta is especially common when talking about time periods that are approaching.

The comma marks the beginning of a subordinate clause.

The main clause is:

• Antaŭ la venonta semajno mi devas decidi
  = Before next week I have to decide

Then comes the clause explaining what must be decided:

• ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo
  = whether I will eat lunch at home or at the office

So the comma helps separate:

• the main statement
• the whether clause

This is very normal in Esperanto.

Here ĉu means whether.

It introduces an indirect yes/no question:

• mi devas decidi, ĉu...
  = I have to decide whether...

This is different from using ĉu at the beginning of a direct yes/no question, such as:

• Ĉu vi venos?
  = Will you come?

So in this sentence, ĉu does not mean the speaker is directly asking someone a question. It introduces the content of the decision.

Manĝos is the future tense, formed with -os.

• manĝas = eat / am eating
• manĝos = will eat

Since the person is deciding now about a future meal, the future tense makes sense:

• ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo
• whether I will eat lunch at home or at the office

Esperanto often uses tenses quite straightforwardly, so if the action is clearly in the future, -os is very natural.

Not in this sentence if you want the same meaning.

• manĝi is the infinitive: to eat
• manĝu is the imperative/jussive form: eat, should eat, or let ... eat
• manĝos is the future: will eat

After ĉu, the clause is stating what may happen in the future, so manĝos is the correct form.

For example:

• Mi devas decidi, ĉu mi manĝos hejme.
  = I have to decide whether I will eat at home.

Using manĝi there would be ungrammatical in normal usage.

The -n ending marks the direct object.

Here, tagmanĝon is the thing being eaten:

• mi manĝos tagmanĝon
• I will eat lunch

In Esperanto, the direct object usually takes -n.

Compare:

• Mi manĝas pomon. = I am eating an apple.
• Mi manĝas tagmanĝon. = I am eating lunch.

So tagmanĝo is the base noun, and tagmanĝon is the accusative form used as the object.

Tagmanĝo means lunch or more literally midday meal.

It is built from:

• tag- = day
• manĝo = meal / eating

So tagmanĝo is the meal eaten during the day, that is, lunch.

Related words include:

• matenmanĝo = breakfast
• vespermanĝo = dinner / supper

They are just two different natural ways of expressing location.

• hejme means at home
• ĉe la oficejo means at the office

Hejme is an adverbial form derived from hejmo (home), and Esperanto often uses -e for location-like adverbial expressions:

• hejme = at home
• urbe = in the city / citywise, in some contexts

But with many places, Esperanto commonly uses ĉe + noun:

• ĉe la oficejo = at the office
• ĉe la kuracisto = at the doctor’s
• ĉe amiko = at a friend’s place

You could sometimes rephrase location in different ways, but the sentence as given sounds very natural.

Ĉe means something like at, by, with, or in the vicinity of, depending on context.

In ĉe la oficejo, it means at the office.

It is a very common preposition in Esperanto and is often used when English uses at:

• ĉe la oficejo = at the office
• ĉe mia amiko = at my friend’s place / with my friend
• ĉe la tablo = at the table

So here it marks the location where the lunch would be eaten.

La is the definite article, meaning the.

In la venonta semajno, it refers to a specific upcoming week:

• the coming week
• the next week

In ĉe la oficejo, it means at the office, referring to a particular office that is understood from context, such as the speaker’s workplace.

Esperanto uses la much like English uses the, though usage is sometimes a bit more regular.

Yes, Esperanto allows fairly flexible word order, though some orders sound more natural than others.

The original sentence is very natural:

• Antaŭ la venonta semajno mi devas decidi, ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo.

You could also say:

• Mi devas decidi antaŭ la venonta semajno, ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo.

That still means essentially the same thing.

Putting Antaŭ la venonta semajno first gives it a bit more emphasis, as if the deadline is important.

Grammatically it links the two alternatives:

• hejme
• ĉe la oficejo

But semantically, of course, the whole decision is between:

• eating lunch at home
• eating lunch at the office

So aŭ directly connects the two location phrases, and that creates the full choice.

A rough pronunciation guide is:

Antaŭ la venonta semajno mi devas decidi, ĉu mi manĝos tagmanĝon hejme aŭ ĉe la oficejo.

Approximate English-style help:

ahn-TAU lah veh-NON-tah seh-MAI-yo mee DEH-vahs deh-TSEE-dee, choo mee mahn-JOHS tahg-MAHN-john HAY-meh ow cheh lah oh-fee-TSEH-yoh

A few useful points:

• ĉ sounds like ch in church
• ĝ sounds like j in judge
• j sounds like y in yes
• ŝ sounds like sh
• ŭ is a short w-like sound, as in aŭ

So:

• ĉu sounds like choo
• ĉe sounds like cheh
• semajno sounds roughly like seh-MAI-yo
• oficejo sounds roughly like oh-fee-TSEH-yo

Yes. It is a very standard and natural construction.

• devi = to have to / must
• decidi = to decide

So:

• mi devas decidi = I have to decide / I must decide

This is one of the simplest and most common ways to express obligation in Esperanto.

Normally, no. Esperanto usually keeps the subject pronoun when it is needed.

So:

• mi devas decidi, ĉu mi manĝos...

is the normal form.

Leaving out the second mi would sound incomplete or unclear, because Esperanto verbs do not change form for person the way many other languages do. Since manĝos alone only tells you the tense, not the subject, the pronoun is usually necessary.

It may look that way from an English perspective, but hejme already means at home.

The ending -e makes it adverbial, and many adverbial forms in Esperanto can express place or manner without an extra preposition.

So:

• hejmo = home
• hejme = at home

That is why no preposition is needed there.

So:

• mi manĝos tagmanĝon hejme
• I will eat lunch at home

is perfectly complete as it stands.