"To restart the device" means to turn it off and then turn it back on again in order to fix any issues or improve its performance. It's like giving the device a fresh start. Full definition
Just restart your device if the same happens to you and use your Pixel device seamlessly. (themrphone.com)
To avail of the update, simply restart the device and it should automatically be searching for the new update. (goodereader.com)
When you press the power button to shut down or restart your device in Android 8.1, the options will no longer take over your entire screen. (greenbot.com)