Verified answer

Обалденно - astounding, awesome.

Sovershenno Potryasaushaia Igra na fleite. Обалденно... - Absolutely amazing flute play. Awesome....

According to google translate,

Awesome

I'm not sure if you mean how is it pronounced/written in English (technically Roman) letters or how it translates into English. It means, "awesome," in English and is pronounced /Obaldenno/ in Russian.

It means 'Awesome' so pronounce it 'or-sum'.

awesome

[aw-suhm]

"Awesome"