This new
ad management feature means that your ad unit settings (such as colors and channels) for new AdSense for content ad units will be
saved in your
AdSense account every time you generate ad code. Then, if you’d like to change any of these settings in the future, all you have to do is to make changes in your adsense account & no need to change the corresponding code on your site's page -
official announcement:
Here
In order to use this feature, you need to create your ads again with the extra option that is supplied when you are creating ads code in your Adsense Account. This option is called
AdSense unit name and will appear at the end of the form!!