On the Actions menu, the Rename 
command renames the selected files and folders.
In the Action subsection, you can select either DOS Compatible or Regular Expressions rename. DOS Compatible expands wildcards using DOS rules. Regular Expressions rename uses Perl-compatible regular expressions.
DOS Rename
To rename files using DOS Compatible Regular Expressions, select files in the Folder Compare view and select Rename from the Actions menu. Select DOS Compatible from the Rename dialog. In the New Mask field, enter the new name.
If multiple files or folders are selected, a base mask is computed which represents the overlap of all the names. An asterisk (*) is used to represent one or more characters, while a question mark (?) is used to represent a single character. Leave these characters alone, but change others to produce unique names for each of the selected files or folders.
Example:
Assume that you've selected the following files to rename:
abc1.txt
abc2.txt
abc3.txt
If you enter "abc?.bak" in the New Name, the files will be renamed to:
abc1.bak
abc2.bak
abc3.bak
Or, enter "xyz?.txt" in the New Name field, and the files will be renamed to:
xyz1.txt
xyz2.txt
xyz3.txt