Task

Action

Select a column

Click on the column heading. 

Select several columns

Drag across column headings.

Or click on first column heading, hold SHIFT down and click on last column heading. All columns between are selected. (While you are dragging, a popup tip shows how many columns are selected like. for three columns)

Hide a column

Set column width = 0

Or choose  Format  |  Column...  |  Hide 

Unhide a column

Drag to select the columns on either side of the hidden one. Choose  Format  |  Column...  |  Unhide 

Change Standard Width

Choose  Format  |  Column...  |  Standard Width...  In the dialog that appears, type in the width (number of characters from 0 to 255) you want for all columns that you have not already adjusted.