La lettera di assunzione include il patto di riservatezza.

Because Italian nouns have grammatical gender.

• lettera is feminine singular, so it takes la
• patto is masculine singular, so it takes il

So:

• la lettera
• il patto

This is one of the first things English speakers have to get used to: articles in Italian change according to the gender and number of the noun.

Here di links two nouns and works a lot like of in English.

• lettera di assunzione = literally, letter of hiring/employment

In natural English, you would usually translate the whole phrase more smoothly, such as employment letter, offer letter, or letter of appointment, depending on context.

This noun + di + noun pattern is extremely common in Italian.

Other examples:

• bicchiere di vino = glass of wine
• corso di italiano = Italian course
• contratto di lavoro = employment contract

So in this sentence, di assunzione specifies what kind of letter it is.

For the same general reason: Italian often uses noun + di + noun where English may use either of or an adjective-like noun.

• patto di riservatezza = literally pact/agreement of confidentiality

In smoother English, that might be:

• confidentiality agreement
• non-disclosure agreement, depending on context

So di riservatezza tells you what kind of patto it is.

This is very normal Italian structure, even when English would not use of.

Because the subject is La lettera di assunzione, which is singular.

The verb is includere = to include.

Present tense:

• io includo = I include
• tu includi = you include
• lui/lei include = he/she/it includes
• noi includiamo = we include
• voi includete = you all include
• loro includono = they include

Since la lettera is a singular thing, Italian uses the third person singular form:

• La lettera ... include = The letter includes ...

No, not exactly. It is spelled the same way, but pronounced the Italian way.

A rough guide is:

• in-CLU-de

The stress falls on -clu-.

A very rough English-style approximation would be something like een-KLOO-deh, though that is only approximate.

A few key points:

• Italian vowels are usually pronounced clearly
• the final e is pronounced
• the word is not reduced the way it often is in English

So don’t read it with normal English pronunciation just because it looks familiar.

In standard Italian, that would sound wrong or at least very unnatural here.

Italian usually uses articles with specific countable nouns like these:

• La lettera
• il patto

So the full sentence naturally keeps them:

• La lettera di assunzione include il patto di riservatezza.

English often drops articles more easily in headings, labels, or note-style writing, but ordinary Italian prose usually does not.

Because includere is a direct transitive verb in Italian.

That means it takes a direct object with no preposition:

• includere qualcosa = to include something

So:

• La lettera di assunzione include il patto di riservatezza.

Not:

• include a il patto
• include nel patto
  unless you are saying something different

This is similar to English, where include also takes a direct object:

• The letter includes the confidentiality agreement.

This is the normal, neutral word order in Italian:

• Subject + verb + object

Here:

• La lettera di assunzione = subject
• include = verb
• il patto di riservatezza = object

Italian word order can sometimes be changed for emphasis, style, or contrast, but this version is the most straightforward and natural for ordinary statement style.

For a learner, this is the safest order to use.

No. This is a classic place where English speakers may be misled by similarity.

In this sentence, assunzione means:

• hiring
• employment
• recruitment

So lettera di assunzione is a letter connected with hiring/employment.

Although assunzione and assumption look similar, they do not match in meaning here.

For assumption in the sense of an idea you take for granted, Italian would more often use supposizione, presupposto, or ipotesi, depending on context.

There are alternatives, depending on tone and legal context.

Possible related expressions include:

• patto di riservatezza
• accordo di riservatezza
• clausola di riservatezza

These are similar but not always identical:

• patto suggests a pact or formal agreement
• accordo is a very common word for agreement
• clausola means a clause, so it refers to a section inside a larger document rather than a separate agreement

So if the confidentiality part is a separate agreement, patto or accordo may fit better.
If it is just one provision inside the hiring letter, clausola di riservatezza may be more precise.

In Italian, the structure strongly suggests that each di + noun phrase modifies the noun immediately before it.

So:

• lettera di assunzione = the letter is what is connected to assunzione
• patto di riservatezza = the patto is what is connected to riservatezza

Then the larger sentence is:

• [La lettera di assunzione] [include] [il patto di riservatezza].

Seeing the sentence in chunks often helps:

• La lettera di assunzione / include / il patto di riservatezza

That makes the structure much easier to understand.