Workflow is where cards live. The Workflow is made up of columns. There are three types of columns; to-do, in progress, done. Each column has one of those types assigned, defining the progress of cards inside the column. You can have as many columns as you'd like, and you can always edit them later on.
Cards live in columns, and move from column to column as the card progresses. That way everybody on the team can get an instant glimpse at how the project is evolving.
Moving columns and cards is super simple. You just drag and drop. For a column, use the 8 dots at the top left of the column, and for cards, simply drag it from anywhere on the card.