When you copy a field using one of the copy buttons in Account View, the field value is copied to the clipboard. Unless you copy something else to the clipboard, this data would remain there for anyone to see. This is where Secure Clipboard can be used.
If enabled, Secure Clipboard will delete the contents of your clipboard after the specified delay if the contents are unchanged. The contents are only overwritten if they are the same as the value which LockCrypt originally copied.
For example: If you copy a field called 'Bank name' and have the delay set to 60 seconds, after one minute, the clipboard contents will be deleted. If, however, you were to copy something else to the clipboard from another application after 30 seconds, LockCrypt would realise the clipboard's contents have changed and leave the current contents intact after 60 seconds have elapsed.