This menu command is only active if you have selected at least two sheets in the document.
To select multiple sheets, click each sheet tab while pressing Command Ctrl or Shift.
In contrast to copying an area to the clipboard, you can filter certain information and calculate values.
Filling a Sheet
Select the entire sheet by clicking the empty gray box in the upper left of the sheet. You can also select an area of the sheet to be copied.
Press CommandCtrl and click the tab of the sheet where you want to insert the contents.
Select the command Sheet - Fill Cells - Sheets. In the dialog which appears, the check box Numbers must be selected (or Paste All) if you want to combine operations with the values. You can also choose the desired operation here.
This dialog is similar to the Paste Special dialog, where you can find additional tips.