Mia kunludanto klarigis la regulon.

The ending -n marks the direct object in Esperanto.

In this sentence, la regulon is the thing that was explained, so it gets the accusative ending:

• regulo = rule
• regulon = rule, as the direct object

So:

• Mia kunludanto = the subject, the person doing the action
• klarigis = explained
• la regulon = what was explained

Because mia kunludanto is the subject, not the object.

Only the direct object takes -n. Here, the fellow player is the one who explained something, so there is no accusative ending.

Also, adjectives and other modifiers agree with the noun they describe. So if this phrase were an object, both words would change:

• mia kunludanto = my fellow player
• mian kunludanton = my fellow player, as the direct object

But in this sentence, the subject is mia kunludanto, so no -n appears there.

Kunludanto is a compound word. Esperanto often builds words by combining meaningful parts.

Here it can be understood as:

• kun- = with, together
• lud = play
• -ant- = someone doing an action
• -o = noun ending

So kunludanto means something like someone who plays with you/another person, which can be translated as fellow player, playmate, or teammate/co-player depending on context.

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

The ending -is marks the past tense in Esperanto.

So:

• klarigas = explains / is explaining
• klarigis = explained
• klarigos = will explain

In this sentence, the action happened in the past, so klarigis is used.

Yes. Klarigi is closely related to klara.

• klara = clear
• klarigi = to make clear, to explain

The important part is -ig-, which often means to cause or make something become.

So klarigi literally means to make clear. That is why it is used for explain.

This is a very useful pattern in Esperanto:

• pura = clean

• purigi = to clean, to make clean

• varma = warm
• varmigi = to warm, to make warm

La is the definite article, like English the.

Esperanto has:

• la = the
• no separate word for a/an

So la regulon means the rule, usually a specific rule that is known from the context.

If you just want to say a rule, Esperanto often simply says regulo without any article.

For example:

• Mi klarigis regulon. = I explained a rule.
• Mi klarigis la regulon. = I explained the rule.

The exact choice depends on context, much as it does in English.

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

The normal order here is:

• Mia kunludanto klarigis la regulon.

But you could also say:

• La regulon klarigis mia kunludanto.

This is still understandable because regulon has -n, so it is clearly the object.

That said, the usual and most neutral order is still subject–verb–object, especially for learners.

Yes, normally it is written as one word.

Esperanto compounds are usually written together:

• kunludanto
• samklasano
• lernejo
• vortaro

Writing kun ludanto would usually suggest two separate words, which changes how the phrase is understood. In standard Esperanto, the compound form kunludanto is the natural choice.

In Esperanto, the stress is almost always on the second-to-last syllable.

So here you get:

• MIA? No — mi-a has two syllables, so stress is on MI
• kun-lu-DAN-to
• kla-RI-gis
• re-GU-lon

More clearly:

• MIA
• kunluDANto
• klaRIgis
• reGUlon

This regular stress pattern is one of the things that makes Esperanto pronunciation easier to predict than English.