Mi vidas insekton sur la folio.

Because insekton is the direct object of the verb vidas.

In Esperanto, the direct object usually takes the ending -n. Here:

• Mi = I
• vidas = see
• insekton = an insect / the insect

So the sentence structure is:

• Mi = the one doing the action
• vidas = the action
• insekton = the thing being seen

Without -n, insekto would just be the basic dictionary form of the noun.

Because la folio comes after the preposition sur, and here it shows location, not a direct object.

• sur la folio = on the leaf

In Esperanto, nouns after prepositions usually do not take -n unless there is a special reason, especially movement toward something.

So:

• sur la folio = on the leaf, located there
• sur la folion = onto the leaf, moving onto it

In your sentence, the insect is already on the leaf, so la folio is correct.

vidas comes from the verb root vid-, which means see.

Esperanto verbs always have regular endings:

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

So:

• vidi = to see
• vidas = see / am seeing / is seeing

In this sentence, vidas means see in the present tense: I see.

No. Esperanto verbs do not change according to the subject.

That means:

• mi vidas = I see
• vi vidas = you see
• li vidas = he sees
• ŝi vidas = she sees
• ili vidas = they see

The verb stays vidas every time. This is one of the easiest parts of Esperanto grammar for English speakers.

la is the Esperanto definite article, meaning the.

So:

• la folio = the leaf

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

Also, Esperanto has no indefinite article. So:

• folio can mean a leaf or just leaf
• la folio means the leaf

In this sentence, la folio suggests a specific leaf.

Because Esperanto does not use an indefinite article like English a or an.

So:

• insekto = an insect / a insect-like noun in general
• insekton = an insect, as a direct object

English needs a or an, but Esperanto usually does not. The idea of indefiniteness is understood from context.

So Mi vidas insekton naturally means I see an insect.

Yes, more freely than in English, because the -n ending helps show what the direct object is.

The normal order is:

• Mi vidas insekton sur la folio.

But other orders are possible, especially for emphasis:

• Sur la folio mi vidas insekton.
• Insekton mi vidas sur la folio.

These still make sense because insekton has -n, which marks it as the object.

That said, the standard and easiest word order for learners is still subject + verb + object.

sur means on or upon.

In this sentence:

• sur la folio = on the leaf

It tells you where the insect is.

Some similar prepositions are:

• en = in
• sub = under
• super = above
• apud = beside
• ĉe = at / by

So sur is the natural choice when something is resting on the surface of something else.

folio is pronounced in three syllables:

• fo-li-o

A rough English approximation is fo-LEE-o, but with clear, pure vowels.

In Esperanto:

• f sounds like English f
• o is a pure o
• li sounds like lee
• the final o is pronounced clearly, not reduced

So do not pronounce it like one compressed English syllable. Say all three syllables clearly: fo-li-o.

Here is the structure:

• Mi = I
• vidas = see
• insekton = insect + -n direct object ending
• sur = on
• la folio = the leaf

So the grammar is:

• subject: Mi
• verb: vidas
• object: insekton
• prepositional phrase: sur la folio

This is a very typical Esperanto sentence pattern and a good example of how clearly the language marks each part.