"Він пенсіонер?"

Translation: Is he a pensioner?

[yaniv93]

Is the "іо" supposed to be a diphthong, or are the vowels pronounced separately?

[Vinnfred]

They are usually two vowels, but in a fast speech it can sound closer to "пенсьонер"

[savasabaka]

it is pronounced without a pause between i and o, if that's what you are interested in.

[Shady_arc]

It is not a diphthong. Just two vowels, one after another.

Diphthongs in Ukranian do not work like that.

[MichaelKor436367]

What is a pensioner?