Ĉiuj gastoj alportas donacon al la festo.

In Esperanto, -j marks the plural.

• gasto = guest
• gastoj = guests

So Ĉiuj gastoj means all guests. The word ĉiuj already suggests more than one, and gastoj also has to be plural to match.

Ĉiuj means all or all of them when talking about more than one person or thing.

Compare:

• ĉiu gasto = each guest / every guest
• ĉiuj gastoj = all guests

A helpful way to think about it:

• ĉiu = each/every one
• ĉiuj = all ones / everyone / all

Here, ĉiuj gastoj refers to the whole group of guests.

Yes. Alportas is built from:

• porti = to carry
• al- = to, toward

So alporti literally means to carry to, and in normal English this is often translated as bring.

Then -as makes it present tense:

• alporti = to bring
• alportas = brings / are bringing / bring

So Ĉiuj gastoj alportas... means that all the guests bring something.

In Esperanto, all present-tense verbs end in -as.

Examples:

• mi alportas = I bring
• li alportas = he brings
• ili alportas = they bring

Unlike English, the verb does not change depending on the subject. So whether the subject is I, you, he, or all guests, the present tense still ends in -as.

The -n marks the direct object. That means it shows what is being brought.

• donaco = a gift
• donacon = a gift (as the direct object)

In this sentence:

• Ĉiuj gastoj = the subject, the ones doing the action
• alportas = bring
• donacon = the thing being brought

So the -n tells you that donacon receives the action of the verb.

Because la festo is not the direct object here. It comes after the preposition al, which means to.

• donacon = the gift being brought
• al la festo = to the party

In Esperanto, nouns after a preposition usually do not take -n just because they follow that preposition.

So:

• al la festo = to the party
  not al la feston in this sentence

The -n is on donacon because that is the direct object.

Yes. La is the definite article, meaning the.

• festo = a party / party
• la festo = the party

Esperanto has only one definite article: la. It does not change for gender, number, or case.

A learner may notice that Esperanto sometimes uses la where English might or might not, depending on context. In this sentence, la festo suggests a specific party that speaker and listener already know about.

Yes, Esperanto word order is fairly flexible because endings show the grammatical roles.

The neutral order here is:

• Ĉiuj gastoj alportas donacon al la festo.

But other orders can be possible for emphasis, such as:

• Donacon ĉiuj gastoj alportas al la festo.
• Al la festo ĉiuj gastoj alportas donacon.

Because donacon has -n, you can still tell it is the direct object. Even so, the original order is the most straightforward and natural for learners.

Because the sentence says each guest brings a gift, not necessarily gifts in the plural.

• donacon = a gift
• donacojn = gifts

So the sentence presents the gift as singular. In many contexts, this implies each guest brings one gift.

If you wanted to say that all the guests bring multiple gifts, you could say:

• Ĉiuj gastoj alportas donacojn al la festo.

A rough pronunciation guide is:

CHY-ooy GAH-stoy ahl-POR-tahs doh-NAH-tson ahl lah FES-to

A few useful sound notes:

• ĉ sounds like ch in church
• j sounds like y in yes
• c sounds like ts
• stress is always on the second-to-last syllable

So:

• Ĉiuj → ĈI-uj
• gastoj → GAS-toj
• alportas → al-POR-tas
• donacon → do-NA-con
• festo → FES-to