What does it do
Sidebar Generator plugin allows you to create unlimited sidebars that you can assign to different pages. All the generated Sidebars will then show in Apperance - Widgets.
Included as a separate plugin
Since it is important that the themes code should be mostly related to design and user experience, all the extra functionality should stay in plugin. This helps you to have a lighter and faster theme since you only activate the plugins you need.
Starting with KLEO version 4.4.1, KLEO uses the sidebar feature using the SQ Sidebar Generator plugin, so it can be enabled only if you need the functionality.
The plugin will be installed from WP Admin -> Appearance -> Kleo Welcome -> Theme addons -> scroll a bit down.
Another way to install recommended plugins in KLEO theme it's from WP Admin -> Appearance ->Install plugins.
Also for the BuddyApp (from 1.6 version above only) and SweetDate (from 3.3 version above only) themes the plugin will be installed from the same location as above.