(someone's) straight man

Translations
человек, который выступает вторым номером в шутке
In their comedy duo, he's always the straight man.
В их комедийном дуэте он всегда выступает вторым номером.
Definitions
A 'straight man' is a term from comedy referring to the person in a comedic duo whose role is to set up jokes and react in a serious or deadpan manner, allowing the other person (the 'funny man') to deliver punchlines or act humorously. The straight man provides contrast and makes the comedic moments more effective.
Words
someone

pronoun
кто то
is

functional word
есть
straight

adjective
серьёзный
man

noun
партнёр