Le contrôleur explique le réacheminement.

Because French usually needs an article before a common noun, especially when that noun is the subject of a sentence.

So le contrôleur is the normal way to say the controller / inspector as a subject.

A useful comparison:

• Le contrôleur parle. = the noun is the subject, so it keeps the article.
• Il est contrôleur. = after être, professions often appear without an article.

So English often says controller, but French usually prefers le contrôleur in a sentence like this.

Here le is the definite article for a masculine singular noun.

It shows that the speaker is talking about a specific rerouting/redirection, not the idea of rerouting in general.

So:

• le réacheminement = a particular rerouting
• un réacheminement = one rerouting, not yet identified
• just réacheminement by itself would usually not work here in standard French

The article tells you:

• le contrôleur
• le réacheminement

In French, the article is often your clearest clue to grammatical gender.

Also, contrôleur is a masculine noun by default. If you needed a feminine form for a female person, you would usually say la contrôleuse.

Explique is the third-person singular present tense of expliquer.

The subject is Le contrôleur, which is singular, so the verb must also be singular:

• j'explique
• tu expliques
• il / elle / on explique
• nous expliquons
• vous expliquez
• ils / elles expliquent

So Le contrôleur explique... means the subject and verb agree correctly.

Because expliquer can take a direct object.

In this sentence, the thing being explained is le réacheminement, so no preposition is needed:

• expliquer quelque chose

If you want to add the person receiving the explanation, French uses à:

• Le contrôleur explique le réacheminement aux passagers.

So the pattern is:

• expliquer quelque chose à quelqu'un

No. It is the standard French declarative word order:

subject + verb + object

So:

• Le contrôleur = subject
• explique = verb
• le réacheminement = direct object

This is the most basic and common sentence structure in French.

Yes. Since it is a direct object, you can replace it with le (or l' before a vowel sound).

So:

• Le contrôleur explique le réacheminement. becomes
• Le contrôleur l'explique.

Notice that the object pronoun goes before the verb in French, which is different from English.

It is a noun built from a verb.

You can break it down like this:

• acheminer = to route / send on / forward
• réacheminer = to reroute / send onward again
• réacheminement = rerouting / redirection / forwarding again

The ending -ment often turns a verb into a noun, similar to how English sometimes uses endings like -ing or nouns such as movement or shipment.

This word sounds fairly formal or technical, especially in transport, logistics, or travel contexts.

A rough guide is:

kon-troh-lur

More carefully:

• con- has a nasal vowel, so it is not pronounced like English con
• trô sounds like troh
• leur has the French eu sound plus an r, which is hard to match exactly in English

If you want an IPA pronunciation, it is approximately: /kɔ̃.tʁo.lœʁ/

A rough guide is:

ray-ah-shuh-meen-mã

A few important points:

• réa- is pronounced in separate parts: ré-a...
• ch here sounds like sh
• the final -ent is not pronounced like English ent
• the ending -ment has a nasal vowel

Approximate IPA: /ʁe.a.ʃə.mi.nə.mɑ̃/

They help with spelling and pronunciation.

• In réacheminement, the é tells you the vowel is pronounced ay-like, not a mute e.
• In contrôleur, the ô is part of the standard spelling of the word. In modern French, it often does not create a huge pronunciation difference for learners, but it is important to write it correctly.

So even when the accent does not dramatically change the sound for an English learner, it still matters in correct French spelling.

Yes, in several common ways:

• Le contrôleur explique le réacheminement ?
  Rising intonation in speech

• Est-ce que le contrôleur explique le réacheminement ?
  Very common in spoken and written French

• Le contrôleur explique-t-il le réacheminement ?
  More formal inversion

This helps show that the original sentence is a normal statement, not a special structure.