know (one's) stuff

Translations
знать свое дело
The new manager really knows her stuff.
Новый менеджер действительно знает свое дело.
Definitions
To be very knowledgeable or skilled in a particular subject or area; to have expertise or competence.
Words
know

verb
знать
one

pronoun
свой
s
притяжательная форма
stuff

noun
дело