They allow the user to browse for more add-ons of all types, as well as allowing Kodi to check them for updates to add-ons, so they don't have to be manually installed.
The first method, and easiest, is if you have Install updates automatically (default) enabled.
With this method, any add-on installed that's in an installed repository will automatically update when there is a new one available.
This is especially helpful via the web-interface and largely possible due to that SINGLE server architecture design.
More readily available in App form on more devices.
In the Add-on manager you can also change the settings for auto update, notifications and search for installed add-ons by bringing up the slide in submenu (press left When an update to an add-on is available it will show up here.
By default, add-ons are set to update automatically, so this should normally be empty unless you have changed your preferences to prevent automatic update installs.The Add-on manager's purpose is to manage the various add-ons to the Kodi application.It can be browsed like any other section and the various installed/uninstalled, enabled/disabled add-ons.(see How to install additional add-on repositories for more info) When the add-on has finished downloading Kodi will enable it and depending on the add-on ask if you want to start using it.Add-ons will then appear in their appropriate section (e.g.By allowing, you agree that you are solely responsible for any loss of data, unwanted behavior, or damage to your device.