Java is a programming language that is used for a lot of applications on your computer. yes it is required and yes it is safe so let it upgrade.
the only issue with the Java upgrades is that it installs the new version, but does not remove the old version. If, after the update, you go to add remove programs in your control panel and look through the list you may see several Java version listed as installed, it is perfectly safe to remove all but the latest one (though if your not sure about doing that then it's also fine just to leave them installed)