Behave suitably for one's position, rank, or status. This idiom often has the sense of “to behave humbly, not criticize ones' superiors,” as in Sorry, I know my place and I can't tell you more about my supervisor's plans. [Late 1500s] Also see put one in one's place.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.