Concept of been + 3rd form of verb

Explain me the concept of been + 3rd form of verb. Is it use in active passive voice?

It’s passive voice. Some active -> passive examples:

“The cat has eaten my dinner” -> “My dinner has been eaten by the cat”

“The police have arrested John” -> “John has been arrested by the police”

“I arrived to find that someone had taken my seat” -> “I arrived to find that my seat had been taken by someone”