The meaning of this sentence is: to serve the country, one must be diligent; to manage the housekeeping, one must be frugal. To put it simply, it means working tirelessly for national affairs and living a frugal life at home.

Be diligent and dedicated to the country: refers to doing your best for the cause of water control. Be frugal at home: live frugally at home.

"Be diligent in your country, be thrifty in your family" This sentence comes from "Shangshu Dayu Mo".

Extended information:

Keqinkexiu is an idiom, which means to be both hard-working and frugal. From "Shang Shu Dayu Mo".

It is recorded in "Dayu Mo" that Emperor Shun praised Dayu: "Be diligent in the state, be thrifty in the family." Shun said to Dayu: You have completed the great cause of water control, worked tirelessly for national affairs, and stayed at home. Live a simple and frugal life; you are not self-satisfied or boastful; you do not boast of your talents, so no one in the world can compete with you; you do not boast of your achievements, so no one in the world can compete with you. So Shun wanted to pass the throne of king to Yu.

Reference materials: Be diligent and thrifty Baidu Encyclopedia