La ĵetkubo apartenas al mi.

Literally, ĵetkubo is a compound word:

• ĵeti = to throw
• kubo = cube

So ĵetkubo is a throw-cube, which is Esperanto’s normal word for a die (the singular of dice).

This kind of word-building is very common in Esperanto.

A simple English-style approximation is:

zheht-KOO-bo

More exactly:

• ĵ sounds like the s in measure or the zh sound in vision
• e is like e in met
• u is like oo in food
• stress in Esperanto normally falls on the second-to-last syllable

So ĵetkubo is stressed on ku: ĵet-KU-bo.

La is the definite article, meaning the.

So:

• ĵetkubo = a die or die in a general sense
• la ĵetkubo = the die

Esperanto has only one article, la. It does not change for gender, number, or case the way articles do in some other languages.

Aparteni means to belong.

The ending -as shows the present tense, so:

• aparteni = to belong
• apartenas = belongs / is belonging

So La ĵetkubo apartenas al mi means The die belongs to me.

In Esperanto, verbs always have regular endings:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command/wish
• -i = infinitive

So apartenas is present tense because the sentence is talking about a current fact: the die belongs to me now.

Because aparteni is used with al, which means to.

So the pattern is:

• aparteni al iu = to belong to someone

Examples:

• La libro apartenas al ŝi. = The book belongs to her.
• La domo apartenas al ni. = The house belongs to us.

You should learn aparteni together with al as a set pattern.

Because after the preposition al, Esperanto uses a personal pronoun, not a possessive adjective.

• mi = me / I
• mia = my / mine-like adjective

So:

• al mi = to me
• mia ĵetkubo = my die

In this sentence, the structure is belongs to me, so al mi is correct.

Yes. That is also correct.

• La ĵetkubo apartenas al mi. = The die belongs to me.
• La ĵetkubo estas mia. = The die is mine.

The meaning is very similar. Often estas mia sounds a bit simpler and more direct, while apartenas al mi emphasizes ownership more explicitly.

The accusative -n is usually used for a direct object or for certain expressions of direction.

In La ĵetkubo apartenas al mi:

• La ĵetkubo is the subject
• apartenas is the verb
• al mi is a prepositional phrase

There is no direct object here, so no accusative -n is needed.

Also, after a preposition like al, you normally do not add -n.

Yes, Esperanto word order is fairly flexible, though some orders sound more neutral than others.

The most natural order here is:

• La ĵetkubo apartenas al mi.

But you could also say:

• Al mi apartenas la ĵetkubo.

That version gives more emphasis to al mi.

Still, for learners, the normal subject-verb-rest order is the safest choice.

It is singular.

In Esperanto:

• singular nouns usually end in -o
• plural nouns add -j

So:

• ĵetkubo = die
• ĵetkuboj = dice

If you wanted to say The dice belong to me, that would be:

• La ĵetkuboj apartenas al mi.

Because Esperanto often prefers transparent, logical compounds.

A die is physically a small cube used for throwing, so ĵetkubo makes perfect sense from its parts. English uses a special historical word, die, but Esperanto often builds vocabulary in a more regular way.

This is one of the reasons Esperanto vocabulary can be easier to learn once you know the common roots.

It is a normal and useful verb, but in everyday speech, Esperanto speakers often also use simpler ownership expressions like:

• ĝi estas mia = it is mine
• tio estas mia = that is mine

So aparteni is not strange or overly formal, but it may sound a bit more explicit than just using mia.

Mia is a possessive form, functioning like an adjective.

It normally appears before a noun:

• mia libro = my book

But it can also stand on its own when the noun is understood:

• La libro estas mia. = The book is mine.

So in La ĵetkubo estas mia, mia means mine, even though its form is the same as my.

Yes, that is a very good idea.

Many Esperanto verbs regularly go with a certain preposition, and aparteni normally goes with al.

So it is best to learn it as:

• aparteni al = to belong to

That will help you avoid mistakes like using the wrong preposition or trying to treat mi as a direct object.