L'assicuratore risarcisce l'assicurato.

The apostrophe shows the definite article l', which means the.

Italian uses l' before a singular noun that begins with a vowel:

• l'amico = the friend
• l'idea = the idea
• l'assicuratore = the insurer
• l'assicurato = the insured person

At the start of the sentence it is written L' with a capital letter only because it comes first.

They come from the same family of words, but they mean different things:

• assicuratore = insurer, the person or company that provides insurance
• assicurato = insured person, the person who is covered by the policy

The ending -tore often refers to the person who does the action, while -ato is often connected to the person or thing affected by the action.

In normal Italian word order, the noun before the verb is usually the subject, and the noun after the verb is the direct object.

So in:

L'assicuratore risarcisce l'assicurato.

• l'assicuratore = the subject, the one doing the action
• risarcisce = the verb
• l'assicurato = the object, the one receiving the action

If you reversed the two nouns, the meaning would change.

Risarcisce is the third person singular present indicative of risarcire.

That means it matches:

• lui risarcisce = he compensates
• lei risarcisce = she compensates
• l'assicuratore risarcisce = the insurer compensates

So here it means compensates, indemnifies, or reimburses for damage/loss, depending on context.

Because risarcire belongs to the group of -ire verbs that add -isc- in some present-tense forms.

Its present indicative is:

• io risarcisco
• tu risarcisci
• lui/lei risarcisce
• noi risarciamo
• voi risarcite
• loro risarciscono

So risarcisce is completely regular for this type of verb.

No.

• assicurare = to insure
• risarcire = to compensate / indemnify / pay for damage or loss

That is an important difference.

So this sentence is not saying that the insurer insures the insured person. It is saying that the insurer compensates or indemnifies the insured person.

Because risarcire is a direct transitive verb. It takes a direct object with no preposition.

So you say:

• risarcire qualcuno = to compensate someone

That is why the sentence is:

L'assicuratore risarcisce l'assicurato.

not a version with a before l'assicurato.

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

But the same form can also be an adjective or past participle in other contexts:

• un veicolo assicurato = an insured vehicle
• una casa assicurata = an insured house

So the form is the same, but its job in the sentence can change.

Yes, in normal Italian you do.

Italian uses definite articles much more often than English. In a sentence like this, leaving them out would sound unnatural.

So Italian prefers:

L'assicuratore risarcisce l'assicurato.

rather than a bare-noun version like English sometimes allows in headlines or very compressed language.

Yes. They change normally for gender and number.

For example:

• L'assicuratrice risarcisce l'assicurata. = The female insurer compensates the female insured person.
• Gli assicuratori risarciscono gli assicurati. = The insurers compensate the insured persons.

So the sentence you have is specifically masculine singular for both nouns.