It's no secret that privacy experts and paranoid citizens alike have a distaste for some of Google's practices, namely the extensive data collection on each user that powers their multi-billion dollar advertising empire. They've also come under fire for their lack of transparency at times and even suffered a class-action lawsuit due to privacy concerns with their Wallet service, but the "My Account" feature, found in the Google App for Android and iOS and in Chrome on PCs, allows you to see what data they may have on you, as well as manage that data and future collection.
To reach this in Chrome, simply click the square apps icon on any Google website and "My Account" should be under "More". The hub here allows you to view and manage your personal data, as well as control account security and content such as Drive. You can also delete your Google account from this page, if you wish.
To reach the "My Account" page on a mobile device, you can go through the Chrome Browser to this address or go through the Google Settings app. In the app, go to the "Personal Info & Privacy" section. From there, you can go to "Your Personal Info" to see Google's data on you, including your web and app activity, location storage, voice search and more from any devices you've signed into. You can also manage this data, delete it or manage future data collection. Nifty features such as downloading or copying your data, as well as assigning an account trustee, call this page home. A link at the bottom of the page allows you to read up on the data Google collects and how it's used.
You can also use the settings under the "Activity controls" heading to dictate what Google can and cannot collect and use. This can include things like your web and app activity, locations, searches, voice history and a history of your searches and watched videos on YouTube. Through this hub, you can also tailor the ads that Google serves you and check out an account overview that shows your personal usage for each service, giving you a better idea of the kind of Google user you are.