In Tableau, the Filters shelf appears above the Marks card and is a place where you can specify which rows of data you want to display in your visual. Users have available on the right the ability to use the check boxes to select which portion of data they want. It is set to Multiple Values (list). To change that, click the down arrow on the right side of the filter control and choose one of the other options.

Category is in the Filters shelf. In the screenshot below you’ll notice the tooltip Office Supplies with the total amount of $719,047.03. I hovered over the orange bar in the middle of the larger bar to see the tooltip.

To make the visual display the category when the user hovers over one of the bars in the bar chart, first click the Label marks card and then click Selected, as shown below.