Ni pasigos tri tagojn ĉe la maro kaj poste du tagojn en la urbo.

Pasigos is the future-tense form of pasigi, which means to spend in the sense of spending time.

• pasigi = to spend time
• pasigas = spend / am spending
• pasigis = spent
• pasigos = will spend

So Ni pasigos... means We will spend...

A learner may expect something based on pasi, but that verb means to pass or to go by. Esperanto often uses pasigi tempon for to spend time.

Here, the -n is used for duration of time.

In Esperanto, a time expression often takes -n when it shows how long something lasts.

So:

• tri tagojn = for three days
• du tagojn = for two days

This is very common:

• Mi laboris du horojn. = I worked for two hours.
• Ŝi restos semajnon. = She will stay for a week.

So in your sentence, the -n does not mean a direct object in the usual English sense. It marks the length of time.

Yes, in one sense it is, because pasigi can take a direct object of time: you spend three days.

But for learners, it is often most helpful to think of this as a duration expression:

• Ni pasigos tri tagojn... = We will spend three days...

So grammatically it behaves like an object, but semantically it tells you how long.

Because ĉe means at, by, or near, while en means in.

So:

• ĉe la maro = at the sea / by the seaside
• en la maro = in the sea

In this sentence, the idea is that the people will spend time at the seaside, not literally inside the water.

This is a very important distinction:

• ĉe la maro = staying near the sea, at the coast
• en la maro = physically in the sea

Because the relationship to the place is different.

• en la urbo = in the city, inside that area
• ĉe la maro = at/by the sea, near it

A city is normally thought of as a place you are inside, so en is natural.

The sea here is being treated more like a nearby location or destination area, so ĉe is natural.

So the prepositions match the meaning:

• ĉe = at/by/near
• en = in/inside

Esperanto uses la for the when the speaker has a specific place in mind, or when the noun is understood in a general but definite way from the context.

Here:

• ĉe la maro often means at the seaside / by the sea
• en la urbo means in the city

This can sound natural even when English might sometimes omit or vary the article depending on context. Esperanto often uses la in set expressions like these when the place is understood.

It does not necessarily mean there is only one sea or one city in the world. It means the place is identifiable in context.

Yes, very often that is the most natural translation.

Literally, it is at the sea or by the sea, but in idiomatic English at the seaside may fit better depending on context.

So these are all possible ways to understand it:

• by the sea
• at the sea
• at the seaside

Poste means afterward, after that, or then.

In this sentence it connects the two parts of the plan:

• first: tri tagojn ĉe la maro
• then: du tagojn en la urbo

So:

• kaj poste = and then / and afterward

Its position here is very natural, but Esperanto word order is fairly flexible. You could also see sentences where poste appears in a slightly different place if the speaker wants a different emphasis.

Because Esperanto often expresses duration simply with the accusative -n.

So instead of saying:

• dum tri tagoj

it is also very common to say:

• tri tagojn

Both can express duration, but the bare accusative form is very typical and concise.

So:

• Ni pasigos tri tagojn ĉe la maro = We will spend three days by the sea.
• Ni pasigos dum tri tagoj ĉe la maro would sound less natural here.

With pasigi, the accusative time expression is especially normal.

Not in normal Esperanto.

Esperanto verbs do not change according to person:

• mi pasigos
• ni pasigos
• ili pasigos

The verb form pasigos only tells you it is future tense. It does not tell you who the subject is.

So you normally need the subject pronoun:

• Ni pasigos... = We will spend...

Without Ni, the sentence would be incomplete unless the subject had already been clearly stated in a special context.

It is pronounced roughly as pa-SEE-gos.

Breaking it down:

• pa as in pah
• si with s, not z
• gos with a clear g

Esperanto stress is always on the second-to-last syllable, so:

• pa-SI-gos

That same stress rule also applies elsewhere in the sentence:

• ta-gojn
• MA-ro
• POS-te
• UR-bo

The sentence has this structure:

• Ni = subject, we
• pasigos = verb, will spend
• tri tagojn = duration, three days
• ĉe la maro = location, by the sea
• kaj poste = connector, and then
• du tagojn = duration, two days
• en la urbo = location, in the city

So the pattern is basically:

We will spend + amount of time + place, and then + amount of time + place.

This is a very useful model for making your own sentences.

For example:

• Ni pasigos semajnon en Parizo kaj poste du tagojn en Romo.
• Ŝi pasigos la someron ĉe la lago.

By itself, maro means sea.

But in the expression ĉe la maro, the whole phrase often refers to the seaside or coastal area in a natural way.

So:

• maro = sea
• ĉe la maro = by the sea / at the seaside

If you wanted to be more specifically physical about the coast, you might choose another word in some contexts, but ĉe la maro is very common and natural for the idea in this sentence.