Turning on Location History and Reporting
Turning this on turns on Location History for your Google Account and if it’s not already on, Location Reporting for this device.
Location Reporting allows Google to periodically store and use your device's most recent location data in connection with your Google Account.
Location History allows Google to store a history of your location data from devices where you are logged into your Google Account and have enabled Location Reporting. You can view and manage your Location History at http://maps.google.com/locationhistory. You can turn off Location History at any point, but doing so won’t delete your Location History. It also will not turn off Location Reporting, GPS or Wi-Fi location services for your device.
Location History and Location Reporting data may be used by any Google app or service, including in ads on and off Google. For example, Google Maps may use it to improve your search results based on the places that you've been.
Learn more about Google Settings.