A sorted bar chart answers "who is first and who is last" before anyone reads the axis. Tableau gives you two ways to sort.
The Sort Ascending and Sort Descending buttons on the toolbar sort the dimension by the measure on the axis. In a horizontal bar chart, Sort Descending puts the biggest bar at the top. A small arrow on the pill shows that it's sorted.
To sort by a different field, right-click the dimension pill and choose Sort.... Pick Field, then the measure and its aggregation, for example Quantity with Sum. The bars keep showing Sales but line up by units sold.
Show Mark Labels (the T button on the toolbar) writes each bar's value on the chart. You can also drag a field to Label on the Marks card to show something other than the bar's own value.