It's a new month which means Nokia Mobile will start rolling out the latest monthly Android Security update to their smartphones. Nokia 7 which is exclusive to China has started receiving the September Android Security update. So, if you have imported a Nokia 7 from China you should definitely check for the latest update.
As per the update notification, the update is just 75MB in size and will require 155MB of free space on the device. The update just brings the Google's September Android Security patch and you can learn more about the latest security patch on Android Security Bulletin.