one or more items can't be changed because they are in use

It means that you're trying to overwrite a file that's open. Without more information, that's all I can tell you.

What kind of data are you copying? Files in your home folder? Applications? System components?

Quit any application in any user account that might have accessed the files. Try again.

Next try a Restart and try again.

Boot in safe mode (shift key down at startup.) Don't launch any applications; just do the copy.

Back up all data, then launch Disk Utility, select the destination volume, and run Repair Disk (not Repair Permissions.) If any problems are found, repeat.

Preceding message was edited after posting.

What is the name of the volume you're copying to?

Launch the Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ If you’re running Mac OS X 10.7 or later, open LaunchPad. Click Utilities, then Terminal in the page that opens.

Drag or copy — do not type — the following line into the Terminal window, then press return:

sudo lsof | grep 'Hard Drive 2'

You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. You don't need to post the warning. If you don’t have a login password, you’ll need to set one before you can run the command.

The command may take a noticeable amount of time to run. Wait for a new line ending in a dollar sign (“$”) to appear.

Post any lines of output that appear below what you entered — the text, please, not a screenshot.

If any personal information appears in the output, edit before posting, but don’t remove the context.