A COP facilitates collaborative planning and combined execution and assists all echelons to achieve situational awareness.
Traditionally, headquarters prepares maps with various symbols to show the locations of friendly and enemy troops and other relevant information.
The term "Common" means it applies to all involved, from highest commander to the lowest soldier to the attached airman.
"Operational" refers to actual, preferably in real-time, status and developments (which rarely fit the plan generated days/hours/moments ago) and it also refers to being at the operational planning level which is a summation and summary of many tactical scales and not of the broader, strategic level.
"Picture" refers to a single, combined, graphics, visual representation of the environment, forces, and actions.