What is pen down means?

Pen down means to write or capture ideas or thoughts onto paper or some other medium using a pen. It can refer to writing down something that was previously discussed or brainstormed or simply jotting down notes or reminders. This phrase is often used to encourage someone to write or record something important in order to ensure that it is not forgotten. It is also a common way of expressing the act of writing, particularly in a creative sense, such as "I need to pen down my thoughts before they slip away."