A wireframe is a simple plan of a page or app screen. It shows where things such as headings, pictures, buttons, and menus might go, before the team decides all the colors and details.
Think of it like the floor plan of a house. It helps people discuss where the rooms go before choosing paint and furniture.
A wireframe can make early feedback easier because people can focus on the order and purpose of the content. It is only a plan, though; it does not show every detail of how the finished page will look or work.