This app is part of the Android Core System Google apps and some non-Google apps require it to run. It is a combination of shared code and background services. A service is an app or process that runs in the background without creating a user Interface also called an activity. The problem with Google play services is that it tends to pick up a lot of data and for an older  smaller device this consumes a lot of the /data partition which prior to Android 4.4 was fixed to a relatively small area. In Android 4.4 and higher the user memory is part of /data and the boundary between /data/ and /sdcard was mounted under /data creating a movable boundry. This gave apps more room.
January 25 2017