When the data required is present in columnar format but you want to use as values then you would pivot the data.
PIvot in the tableau is an easy procedure, Select the columns that you would like to pivot and click on the pivot.
Now you would see 2 new columns pivot field names and pivot field values.
The pivot column fields contain the columns that you performed pivot and the pivot column values contain the values of those columns against each column.
You can read this blog for more information.