The release notes of the software are as follows:
This version of iTunes resolves an issue where the equalizer may not work as expected and improves performance when switching views in large iTunes libraries. This update also includes additional minor bug fixes.
Note: If you are using OS X Mavericks, your book library can now be found in iBooks for Mac.
You can download the latest version of iTunes by heading over to the Mac App Store website and navigating through the ‘Updates’ tab. Alternatively, you can also use this link for the purpose.