Ŝi volas kandidatiĝi hodiaŭ.

Because volas is the finite verb of the sentence: it agrees with the subject ŝi and shows present time.

• voli = to want (infinitive)
• volas = wants

In Esperanto, when one verb is conjugated, a following verb often stays in the infinitive:

• Ŝi volas kandidatiĝi. = She wants to run / become a candidate.

This works much like English wants to run, where wants is the main conjugated verb and to run stays in the infinitive.

Because it comes after volas.

After verbs like voli (to want), povi (to be able), devi (must / have to), Esperanto normally uses the infinitive for the second verb:

• Mi volas iri. = I want to go.
• Ŝi povas veni. = She can come.
• Ni devas atendi. = We must wait.

So in your sentence:

• Ŝi volas kandidatiĝi.
  literally: She wants to become-a-candidate / run.

kandidatiĝi means to become a candidate, to stand as a candidate, or in many contexts to run (for a position or office).

It is built from:

• kandidato = candidate
• -iĝ- = a suffix meaning become, come to be, or get into a state
• -i = infinitive ending

So:

• kandidatiĝi = to become a candidate / to put oneself forward as a candidate

Depending on context, English might translate it as:

• to run
• to stand for election
• to apply as a candidate

-iĝ- often means that something becomes something or enters a new state.

Examples:

• ruĝa = red

• ruĝiĝi = to become red, to blush

• edzo = husband
• edziĝi = to get married (for a man; literally to become a husband)

So:

• kandidato = candidate
• kandidatiĝi = to become a candidate

For English speakers, -iĝ- is very useful because it often corresponds to become, get, or sometimes a natural intransitive change.

ŝi is pronounced roughly like shee in English.

A few details:

• ŝ sounds like English sh
• i sounds like ee

So:

• ŝi ≈ shee

It means she.

hodiaŭ is pronounced approximately hoh-DEE-ow.

Useful points:

• Esperanto stress is usually on the second-to-last syllable
• In hodiaŭ, the stress falls on di
• aŭ is a diphthong, sounding roughly like ow in cow

So the word breaks roughly as:

• ho-di-aŭ

with the stress on di.

Because there is no direct object here.

The sentence has:

• Ŝi = subject
• volas = main verb
• kandidatiĝi = infinitive verb
• hodiaŭ = adverb of time

No noun here is functioning as a direct object, so no accusative -n is needed.

Also:

• hodiaŭ is already an adverb, so it does not need -n
• ŝi is the subject, so it stays ŝi, not ŝin

Yes. Esperanto word order is fairly flexible, especially for adverbs like hodiaŭ.

All of these are possible:

• Ŝi volas kandidatiĝi hodiaŭ.
• Hodiaŭ ŝi volas kandidatiĝi.
• Ŝi hodiaŭ volas kandidatiĝi.

The most neutral version is probably the original one, but moving hodiaŭ can change what feels emphasized.

For example:

• Hodiaŭ ŝi volas kandidatiĝi.
  emphasizes today

It has a reflexive-like meaning in English, but Esperanto expresses that idea with the suffix -iĝ-, not with sin.

So instead of saying something like make oneself a candidate, Esperanto simply says:

• kandidatiĝi = become a candidate / put oneself forward

You use sin when there is an actual reflexive object:

• Ŝi vidas sin. = She sees herself.

But in Ŝi volas kandidatiĝi, there is no reflexive object. The idea is built into the verb itself.

The natural reading is:

• She wants to become a candidate / run today.

So hodiaŭ modifies the action kandidatiĝi most naturally.

In practice, listeners will understand that today is the time of the intended action. If context matters, Esperanto can always make things clearer by rewording, but this sentence is normal and straightforward.

Yes. Its core meaning is to become a candidate, but the best English translation depends on the situation.

Possible translations include:

• to run (especially in elections)
• to stand as a candidate
• to apply as a candidate

So if the context is political, Ŝi volas kandidatiĝi hodiaŭ might mean:

• She wants to run today.

If the context is an application or selection process, it could be closer to:

• She wants to apply as a candidate today.

The sentence breaks down like this:

• Ŝi = she (subject)
• volas = wants (main verb, present tense)
• kandidatiĝi = to become a candidate / to run (infinitive)
• hodiaŭ = today (adverb of time)

So the structure is:

• subject + finite verb + infinitive + adverb

This is a very common Esperanto pattern:

• Mi volas manĝi nun. = I want to eat now.
• Li provas lerni rapide. = He is trying to learn quickly.