Il perito legge la polizza mentre quantifica il danno.

In this context, perito means an expert assessor, often specifically a claims adjuster, surveyor, or insurance expert.

The exact English translation depends on the field:

• in insurance: claims adjuster or loss adjuster
• in legal/technical contexts: expert or court-appointed expert
• more generally: specialist

So here, because the sentence mentions polizza and danno, it clearly sounds like insurance language.

Italian uses definite articles much more often than English.

So:

• Il perito = the adjuster / the expert
• la polizza = the policy
• il danno = the damage / the loss

In English, you might sometimes drop the depending on style, but in Italian these articles are very natural and usually necessary.

For example, Italian often says:

• Leggo il giornale = I read the newspaper
• Chiudi la porta = Close the door

Even where English can sometimes sound more general, Italian still tends to keep the article.

Here legge is the verb reads, from leggere = to read.

That can confuse learners, because legge is also the noun law.

So:

• la legge = the law
• lui/lei legge = he/she reads

In this sentence, it must be the verb, because it comes right after the subject Il perito.

So the structure is:

• Il perito = subject
• legge = verb
• la polizza = object

Polizza usually means a policy, especially an insurance policy.

Very common phrases are:

• polizza assicurativa = insurance policy
• numero di polizza = policy number

So la polizza here is the insurance contract/document the expert is reading.

Mentre means while, and it shows that the two actions happen at the same time.

So the sentence means that:

• the expert reads the policy
• at the same time, he/she assesses the damage

That is exactly the kind of link mentre is used for.

Compare:

• mentre = while
• quando = when

If you used quando, it would sound more like one action happens at the time of the other, not necessarily as two parallel ongoing actions.

Both verbs are in the present indicative:

• legge = reads
• quantifica = quantifies / assesses

Italian often uses the simple present in places where English might use either:

• the simple present: reads
• or the present continuous: is reading

So this sentence can sound like:

• a general description of what the adjuster does
• or a live/process description, depending on context

Italian does have a progressive form, like:

• sta leggendo = is reading

But the simple present is very common and natural.

Here are the present-tense forms:

Leggere = to read

• io leggo
• tu leggi
• lui/lei legge
• noi leggiamo
• voi leggete
• loro leggono

Quantificare = to quantify / assess

• io quantifico
• tu quantifichi
• lui/lei quantifica
• noi quantifichiamo
• voi quantificate
• loro quantificano

A useful pattern:

• leggere is not a regular -ere verb in all forms, so it is worth memorizing.
• quantificare is an -care verb, so it adds h in forms like quantifichi and quantifichiamo to keep the hard k sound.

Literally, it means quantifies the damage, but in natural English this often means:

• assesses the damage
• estimates the damage
• calculates the extent/value of the damage

In insurance language, quantificare il danno often means determining how serious the damage is, especially in financial terms.

So this is a professional, technical use of quantificare, not just a mathematical one.

Il danno refers to the damage as a single overall loss or instance of harm.

Italian often uses the singular when talking about damage in a general or collective sense in a specific case.

So:

• il danno = the damage, the loss, the harm
• i danni = the damages / the various kinds of damage / multiple damaged elements

For example:

• quantificare il danno = assess the damage in a case
• valutare i danni all’edificio = assess the damages to the building / the different parts that were damaged

Both are possible, but il danno is very natural if the speaker is thinking of the loss as one claim or one overall amount.

Yes. Italian word order is more flexible than English.

You could also say:

• Mentre quantifica il danno, il perito legge la polizza.

This still means the same thing: While assessing the damage, the adjuster reads the policy.

The original order is straightforward and neutral:

• Il perito = who is doing the action
• legge la polizza = first action
• mentre quantifica il danno = simultaneous action

Changing the order can shift emphasis slightly, but the basic meaning stays the same.