"[get] down to brass tacks"의 정의 및 의미

What is the origin of the idiom "get down to brass tacks" and when to use it?

The exact origin of the idiom "get down to brass tacks" is uncertain, but it is believed to have originated in the United States in the mid-19th century. It refers to the use of brass tacks to fasten upholstery or other materials to furniture. When someone was "getting down to brass tacks," they were getting down to the essential details or fundamentals of something. It is often used to urge people to stop talking about general ideas or theories and start talking about specific plans or actions.