Supposing you have a table as below screenshot shown, and you can follow below steps to create a pivot table in Excel, and group time data by hour easily.

1. Select the source data, and click Insert > PivotTable.

2. In the Create PivotTable dialog box, please select a destination range to place the pivot table, and click the OK button. See screenshot:

3. In the PivotTable Fields pane, please drag and drop the Time field to the Rows section, and then drag and drop the Amount field to the Values section. See screenshot:

4. Now the pivot table is added. Right-click any time in the Row Labels column, and select Group in the context menu. See screenshot:

5. In the Grouping dialog box, please click to highlight Hours only in the By list box, and click the OK button. See screenshot:

Now the time data is grouped by hours in the newly created pivot table. See screenshot:

Note: If you need to group time data by days and hours simultaneously, please click to highlight Days and Hours in the By list box of the Grouping dialog box, and then click the OK button. See screenshot:

If you need to group time by half an hour in a pivot table in Excel, you can try the amazing PivotTable Special Time Grouping tool, provided by Kutools for Excel, to achieve it easily.

1. Select the data source that you will create a pivot table based on, and click Kutools Plus > Pivot Table > PivotTable Special Time Grouping.

2. In the PivotTable Special Time Grouping dialog, you need to:
(1) Tick the Half an hour option in the Group by list box;
(2) Specify the time column that you will grouping data by;
(3) Specify the location you will place the new pivot table.

3. Click the Ok button.

4. Then a pivot table is created with a Half an hour column added as rows. Go ahead to add the Amount column as values.

So far, the pivot table has been created based on the selection, and data has been grouped by half an hour as above screenshot shown.

Easily groups cells and calculate by values in another column in Excel

With Kutools for Excel’s Advanced Combine Rows feature, you can quick group all cells of one column based on values in another column, or calculate (sum, count, average, max, etc.) these cells by the values in another column at ease!