L’assureur appelle l’assuré.

Because French shortens le and la to l’ before a vowel sound. This is called elision.

So:

• le assureur becomes l’assureur
• le assuré becomes l’assuré

In normal French, you must use l’ here, not the full article.

French normally uses subject + verb + object word order, just like English.

So in:

L’assureur appelle l’assuré.

• l’assureur = the subject, the one doing the calling
• appelle = the verb
• l’assuré = the direct object, the person being called

The first noun is the caller; the second noun is the person called.

They come from the same word family, but they mean different roles.

• assureur = the insurer, the insurance company or insurer
• assuré = the insured person, the policyholder, or the person covered by insurance

The endings help:

• -eur often names the person or thing that does something
• -é is often a past participle and can describe someone affected by the action

So these two words are related, but they are not interchangeable.

Because appeler takes a direct object when you call someone.

You say:

• appeler quelqu’un = to call someone

Not:

• appeler à quelqu’un

This works much like English to call someone.

Appelle is the 3rd person singular present tense form of appeler.

Here are a few present-tense forms:

• j’appelle
• tu appelles
• il/elle appelle
• nous appelons
• vous appelez
• ils/elles appellent

Since l’assureur is singular, the verb is appelle.

That is part of the verb’s normal conjugation pattern.

With appeler, the singular forms and ils/elles use ll:

• j’appelle
• tu appelles
• il/elle appelle
• ils/elles appellent

But nous and vous keep the simpler stem:

• nous appelons
• vous appelez

This is just a spelling pattern you need to learn with the verb.

The endings sound quite different:

• l’assuré ends in -é, pronounced roughly like ay
• l’assureur ends in -eur, a different French vowel sound followed by r

A rough pronunciation of the full sentence is:

/la.sy.ʁœʁ a.pɛl la.sy.ʁe/

The most important contrast to hear is:

• assureur → ends with -eur
• assuré → ends with -é

Not in this exact form.

• l’assuré = masculine singular
• l’assurée = feminine singular

Because both use l’, the article itself does not show gender here. The ending of the noun does:

• -é = masculine
• -ée = feminine

So if the insured person were female, you would write l’assurée.

Here it is being used as a noun: the insured person.

But grammatically, assuré is also the past participle of assurer, and it can also be used as an adjective in other contexts.

So:

• as a noun: l’assuré
• as an adjective: une personne assurée

French often turns past participles into nouns like this.

The é tells you the final vowel is pronounced clearly, like ay.

So:

• assuré ends with a pronounced é
• without that accent, the spelling would suggest something different

The accent is part of the standard spelling and pronunciation of the word.