Services Google Play and Shop Google Play why both?
Google Play Services is a library used by other Google and third-party apps. It allows apps to use:


Google Maps layers to show maps in other apps
Google+ sign-on and sharing
the new Google+ gaming functionality for match-making, leaderboards, and to store saved games "in the cloud"
Google Cloud Messaging to sync data from the Internet to your device efficiently
Location services to set up "geo-fences" so they can respond to locations and activities more efficiently than if they accessed your location directly


It's a lot of functionality that could have been made part of Android itself, but making it a separate library allows Google to update it directly, so app developers can rely on it being up-to-date on every device: unlike Android itself, which some manufacturers and carriers don't bother to update for older devices.

If you were to remove it, any apps that rely on it would stop working or behave unpredictably.