One method is to select the cell you want it copied to and enter = sign in
the formula bar then change sheets while still in the formula bar to the
source sheet and click on the required cell and then press enter.
Another method is to copy the cell in the first sheet and then select the
second sheet and select the cell that you want it copied to and right click
and select paste special, paste link (bottom left of dialog box).
Another way if it is a one off and you don't want to do it as above with
links, you can select both sheets by holding the Ctrl key while you select
the second one. Any changes made to the first sheet are reflected in the
second one.
Regards,
OssieMac