Grouping columns in Excel 2013 places them into collapsible sections, similar to the way Windows displays folders in the navigation pane. Collapsing a group doesn't erase the data contained within, and formulas that reference cells in the collapsed area work without interruption. Collapsing columns is a purely visual effect meant to help simplify large spreadsheets.
Click and drag on the lettered column headings to select the columns you want to group. If you're going to make subsequent subgroups, start with the largest group of columns.
Open the Data tab and click the Group icon in the Outline section to create the first group.
Select a subset of the columns in the original group and click Group again to create a subgroup. Repeat this step as many times as necessary to create all the parallel subgroups and levels of subgroups you need, up to eight levels.
Click a - button to collapse the group of columns indicated by the bracketed area. Collapsed groups display a + button. Click the + to expand a collapsed group.
Excel also has a method of creating groups that works to find useful groupings automatically. For example, in a spreadsheet of labels, values and totals, Excel will create a group that hides all columns except for the labels and the totals.
To use this method, select any cell within your data, open the Group drop-down menu and click Auto Outline.