Columns and Rows Shelves

The Columns shelf creates the columns of a table, while the Rows shelf creates the rows of a table. You can place any number of fields on these shelves.
When you place a dimension on the Rows or Columns shelves, headers for the members of that dimension are created. When you place a measure on the Rows or Columns shelf, quantitative axes for that measure are created. As you add more fields to the view, additional headers and axes are included in the table and you get an increasingly detailed picture of your data.
In the view shown below, the members of the Customer Segment dimension are displayed as column headers, while the Profit measure is displayed as a vertical axis.

Tableau displays data using marks, where every mark corresponds to a row (or a group of rows) in your data source. The inner fields (that is, the fields farthest to the right) on the Rows and Columns shelves determine the default mark type. For example, if the inner fields are a measure and a dimension, the default mark type is a bar. You can manually select a different mark type using the Mark menu. See Mark Types for more information.
Adding more fields to the Rows and Columns shelves adds more rows, columns, and panes to the table.

Hide Rows and Columns

Generally you will add dimensions and measures to create the rows and columns of the table and you’ll either include all data or add filters to only show a subset. However, when you filter data it is also excluded from calculations and other computations performed on the summarized data in the table. Instead of filtering the data, you can hide the row or column so it doesn't display in the view but it is still included in calculations.
Hiding columns is especially useful when using table calculations that compare to previous or next. In that case, there is always a row or column that doesn’t show data because there is no data to compare to. You can simply hide the empty column without modifying the table calculation. For example, when calculating year-over-year growth, the first year doesn't have a previous year to compare to, so the column is left blank. Filtering the first year will remove it from the view but it will also remove it from the calculation so now the second year doesn't have a previous year to compare to and is left blank. Instead of filtering, you can hide the column that you don’t want to show without changing the calculation.
To hide a row or column:

Right-click the row or column you want to hide and then select Hide.

To show hidden data:

Open the field menu for a field that has hidden columns or rows and select Show Hidden Data.