The manufacturing process of 'just-in-time' introduced the concept of kanban. In Japanese, kanban means "a visual sign". Kanban is a visual management tool for handling the flow of work. Work for value through prioritization, and smoothing out workflow/process issues that interfere with consistency.
Visualize what is being worked on today (workflow), as compared to yesterday and tomorrow. Schedule work based on the amount of work that is possible (wip work-in-progress) to complete within the constraint of resources available. Look for ways to improve flow through shorter work cycles, better use of resources, improved management, more collaboration, and learning opportunities. Monitoring workflow is an opportunity to improve efficiency where possible and recognize the most onerous and repetitive tasks that could be automated.
Scrum and Kanban are very complementary.