A slicer is a visual that filters the other visuals on the page. Readers click a value and every chart, table and card updates. To add one, click an empty part of the canvas, pick the Slicer icon (a funnel) in Visualizations and give it one field.
Text fields show as a vertical list. Click a value to select only that value; hold Ctrl (Cmd on a Mac) and click to add more. When nothing is selected, nothing is filtered. Number and date fields start as a Between range with two boxes. To pick single years instead, change the style in Format visual > Slicer settings > Style to Vertical list, Tile or Dropdown.
A slicer filters through relationships, so a Region slicer from the Store table also filters the sales rows. That's why the model's relationships matter; you'll work on them later in the course.