Il responsabile della sicurezza attiva e disattiva la sirena.

Here responsabile is a noun, not an adjective. It means the person in charge, the manager, or the officer responsible.

So il responsabile della sicurezza means something like:

• the person responsible for security
• the security manager
• the security officer

In other contexts, responsabile can also be an adjective meaning responsible.

• È una persona responsabile = He/She is a responsible person

But in your sentence, it is clearly a noun.

Italian usually uses the definite article more often than English.

• il responsabile = the person in charge / the manager

Without the article, responsabile would sound incomplete in this sentence. Italian normally wants the noun phrase to be fully formed.

So:

• Il responsabile della sicurezza... = The security manager/officer...

Della sicurezza means of security or more naturally in English, for security / in charge of security.

It is made of:

• di = of
• la = the
• di + la = della

So:

• il responsabile della sicurezza
  literally = the person in charge of the security

In smoother English, we usually say:

• the security manager
• the person responsible for security

Because sicurezza here is a specific field or area, and Italian commonly uses the article in this structure.

• responsabile della sicurezza = standard Italian

This is very common with job titles and roles:

• il direttore della banca = the manager/director of the bank
• il capo del reparto = the head of the department
• il responsabile della sicurezza = the person in charge of security

English often leaves out the in phrases like security manager, but Italian usually keeps the article inside the phrase.

They are verbs in the present tense, third person singular.

From:

• attivare = to activate, to turn on
• disattivare = to deactivate, to turn off

So:

• attiva = he/she activates, turns on
• disattiva = he/she deactivates, turns off

Because the subject is il responsabile, both verbs mean:

• the security officer activates and deactivates...

Yes, attiva can also be an adjective meaning active, but not in this sentence.

For example:

• La modalità è attiva = The mode is active
• La donna è molto attiva = The woman is very active

In your sentence, attiva comes after the subject and is followed by e disattiva, so it is clearly a verb:

• Il responsabile ... attiva e disattiva la sirena

Because in Italian, just like in English, one subject can govern two verbs joined by e.

So:

• Il responsabile ... attiva e disattiva la sirena

means:

• The person in charge activates and deactivates the siren

Italian does not need to repeat il responsabile before the second verb.

It can mean either, depending on context.

• sirena = siren / alarm siren
• sirena = mermaid

In this sentence, because of security and activate/deactivate, it clearly means the alarm siren.

Again, Italian often uses articles where English may or may not.

• la sirena = the siren

Since this sentence refers to a specific siren, the article is natural and expected.

Italian generally likes explicit articles with countable nouns:

• accende la luce = turns on the light
• apre la porta = opens the door
• attiva la sirena = activates the siren

It is in the present indicative.

• attiva
• disattiva

This tense can mean different things depending on context, for example:

• a habitual action: The security officer activates and deactivates the siren
• a general job duty: The security officer is responsible for activating and deactivating the siren
• something happening now, in the right context: The security officer is activating and deactivating the siren

Italian present tense often covers both simple present and sometimes present continuous ideas that English separates.

Yes. The sentence has a very normal Italian word order:

• Il responsabile della sicurezza = subject
• attiva e disattiva = verbs
• la sirena = object

So it follows the basic pattern:

• Subject + Verb + Object

This makes it a straightforward sentence for learners.

Yes, absolutely.

A very literal translation is:

• activates and deactivates the siren

A more natural English translation in many contexts is:

• turns the siren on and off

Both reflect the Italian well.

Because the same object belongs to both verbs.

So:

• attiva e disattiva la sirena

means:

• activates the siren and deactivates the siren

But repeating la sirena would be unnecessary. Italian, like English, usually mentions the object once when it applies to both verbs.

In Italian, subject pronouns are often omitted because the verb ending already gives information.

So instead of:

• Lui attiva e disattiva la sirena

Italian often simply says:

• Attiva e disattiva la sirena

If the subject is already known.

But in your sentence, the full noun phrase is used because the speaker wants to identify exactly who does the action:

• Il responsabile della sicurezza attiva e disattiva la sirena

Yes. Disattivare is built from attivare with the prefix dis-, which often gives the idea of reversal, removal, or undoing.

• attivare = to activate
• disattivare = to deactivate

This pattern is useful in Italian vocabulary:

• connettere = to connect

• disconnettere = to disconnect

• attivare = to activate
• disattivare = to deactivate

So if you know attivare, disattivare is easy to understand.

Yes, e is the normal word for and.

• e = and

Sometimes you may see ed before a word beginning with e, mainly to avoid the sound clash:

• ed è
• ed entra

But in modern Italian, e is the default form, and before disattiva there is no reason to use ed.

So:

• attiva e disattiva is completely normal.