When you use Google sites, apps and services, your activity is saved in your Google account and stored away on Google servers. But you can find out everything Google has on you by visiting https://myactivity.google.com/myactivity. It allows you to review and delete any data Google saved about you and your online activities. You can also change collection preferences to protect your privacy. Whether this data is really removed from Google servers is up for debate but it would stop a hacker finding out a lot about your life.