Developer option on your G5 Plus is turned off by default. You may not need this unless you need to perform any serious actions. This will generally be used by the Android developers to run or debug their application.
If you want to keep your screen awake while charging and you want to perform any system updates automatically, you can do this when the developer option is enabled. You can increase or decrease the Window or Transition animation scale. You can also view the Running services which will help you monitor the list of applications running in the background.
To enable this option, go to Settings -> About Phone and tap the Build number 7 times. You will get a message the Developer Option is enabled.
Again you can turn off the developer option by tapping the on / off switch at the top of the screen.