It's a term in interior design that we will draw a sketch either hand-drawn or from computer on a empty floor plan to show you the position and rough shapes of various areas and/or joinery items so that our client would under which area on the plan is for what functionality, here we also call it space mix. For example, a typical space plan we do for our office client includes a floor plan sketch as well as a table highlighting different areas, e.g. reception, breakout space, meeting room - 1PAX, 2 PAX, 3PAX...etc., open office area, manager's office...etc.