flat on (someone's) back

Translations
лежать пластом
He was flat on his back for a week after the surgery.
Он лежал пластом неделю после операции.
Definitions
In a position of lying down with one's back touching the ground or a surface, often implying helplessness, incapacitation, or rest.
Words
flat

adverb
лежа
on

preposition
на
someone

pronoun
кого то
is

functional word
есть
back

noun
спина