📌 General Meaning

• A brief instruction given to a person who will carry out a task, summarizing expectations and objectives.

📌 In Design / Advertising / Marketing

• Before a project starts, the information given by the client or manager about the project includes:

  • the goal,

  • target audience,

  • delivery date,

  • desired style,

  • materials to be used,

  • must-have points
    such as the information contained in the document.

📌 In Law

• Refers to a brief summary or presentation document prepared by a lawyer regarding a case or situation.

📌 In Daily Use

• It is also used in the meaning of "to explain briefly".
  For example: "What will we do briefly?" = "What will we do in short?"

If you want, I can also prepare a sample brief.