En nia hejmo estas kutimo prepari vespermanĝon kune, kiam ni havas tempon.

En nia hejmo means in our home or in our household.

A native English speaker may expect house, but hejmo is closer to home in the sense of family life and the place where people live together. Domo is more the physical building: house.

So:

• hejmo = home, household
• domo = house, building

In this sentence, hejmo is a good choice because the sentence is about a family custom, not just about a building.

Because en here shows location, not movement.

In Esperanto, after a preposition like en, you normally do not use -n unless there is movement toward something.

So:

• en nia hejmo = in our home
• en nian hejmon = into our home

Here the meaning is static location, so hejmo stays without -n.

Esperanto often leaves out the kind of dummy subject that English uses.

In English, we say It is a custom..., but that it does not really refer to anything. Esperanto usually does not need such a word, so estas kutimo is perfectly natural.

So:

• English: It is a custom
• Esperanto: estas kutimo

The sentence could be understood as something like In our home, it is customary... or In our home, there is a custom...

Because Esperanto has:

• la = the
• no word for a/an

So a bare noun like kutimo can mean a custom or custom depending on context.

Here estas kutimo means it is a custom / there is a custom.
If it said estas la kutimo, that would mean it is the custom, referring to a specific, already known custom.

Because kutimo can be followed by an infinitive to show what the custom or habit is.

So:

• kutimo prepari vespermanĝon = the custom of preparing dinner
• literally: a custom to prepare dinner

This is a normal Esperanto pattern. The infinitive prepari explains the action connected with the custom.

You could compare:

• Estas plezuro lerni. = It is a pleasure to learn.
• Estas kutimo prepari vespermanĝon kune. = It is a custom to prepare dinner together.

Yes. That would also be correct, but it is not exactly the same in tone.

• En nia hejmo estas kutimo prepari vespermanĝon kune focuses on the idea of a household custom/tradition.
• Ni kutime preparas vespermanĝon kune simply says we usually prepare dinner together.

So the original sentence sounds a bit more like describing a family practice or tradition, not just a repeated action.

Because it is the direct object of prepari.

The verb prepari means to prepare, and the thing being prepared is vespermanĝo. Direct objects in Esperanto take -n.

So:

• prepari vespermanĝon = to prepare dinner
• vespermanĝo = dinner / evening meal
• vespermanĝon = dinner as the object

This is one of the most basic uses of the accusative -n.

Vespermanĝo is a compound word:

• vespero = evening
• manĝo = meal, eating

So vespermanĝo literally means evening meal. In English, that is usually dinner or supper, depending on dialect and context.

Esperanto often forms words this way, by combining meaningful parts into one clear compound.

Because kune is an adverb meaning together.

• kune describes how the action is done
• kun is a preposition meaning with, and it must be followed by a noun or pronoun

So:

• Ni preparas vespermanĝon kune. = We prepare dinner together.
• Ni preparas vespermanĝon kun amikoj. = We prepare dinner with friends.

In this sentence, the subject is already ni, so kune is enough.

Both are possible, but they give slightly different nuances.

• kiam ni havas tempon = when / whenever we have time
• se ni havas tempon = if we have time

Kiam sounds more like describing the occasions on which this custom happens.
Se sounds more conditional and uncertain.

In this sentence, kiam fits well because it describes a regular habit that happens on the occasions when time is available.

Havi tempon literally means to have time, just like in English.

Here tempo is the direct object of havas, so it takes -n:

• ni havas tempon = we have time

This is a very common Esperanto expression. English speakers sometimes look for a structure like are free, but havi tempon is completely normal and idiomatic.

Esperanto word order is fairly flexible.

The original sentence:

En nia hejmo estas kutimo prepari vespermanĝon kune, kiam ni havas tempon.

puts the setting first: In our home...

Other possible versions include:

• Prepari vespermanĝon kune estas kutimo en nia hejmo.
• En nia hejmo ni kutimas prepari vespermanĝon kune, kiam ni havas tempon.

These are all understandable, but they place emphasis a little differently. The original version sounds natural and slightly formal, with focus on the household custom.

Because kiam ni havas tempon is a subordinate clause.

Esperanto often uses commas to separate subordinate clauses from the main clause, especially when the sentence is a bit long. So the comma helps show the structure clearly:

• main idea: En nia hejmo estas kutimo prepari vespermanĝon kune
• time clause: kiam ni havas tempon

So the comma is natural and helpful here.