The Kanban board visualzes the workflow, especially the progress of each ticket (task). A Kanban board can be a physical board, such as a magnetic board; it is, however, common to have a digital Kanban board in programs such as JIRA or VersionOne. Visualization means that it is made visible on which tasks a Kanban team is currently working on and what the status of the each tasks is.
Fig.: Kanban Board
Typically, it is assumed that all tasks go through the same stages (process steps, workflows). In software development, this begins with the analysis of a requirement, then it's development, testing and release. These process steps are visualized on a Kanban-Board by vertical columns, the tasks pass as tickets (index cards on a pyhsical Kanban Board) from left to right through the different process steps. A card can also contain various additional information: For example, the urgency, the type of task (e.g. "new feature" or "bug") or the owner of the task (for example, a photo of the current person is placed on the ticket).
Kanban is based on the pull principle, i.e.: A team member fetches tickets from the previous process step, i.e. tickets are not simply moved to a new process step. In this way, blockages or bottlenecks become transparent.
If there is a clear number of task types or sources of tasks (e.g. new feature requests, bugs, change requests), then it makes sense to adjust the structure of the Kanban board. For these cases so-called "Swim Lanes" are created, this divides the Kanban Board horizontally. A ticket of the task type "New Feature" then moves from process step to process step within a "Swim Lane" dedicated to "New Features".