Recovery, in Android, refers to the bootable partition, in which the recovery console is installed.
It contains tools to help repair your installations as well as install official OS updates by using a combination of key presses or instructions from a command line sometimes.
Android is open, meaning the recovery source code is available, so that building a customized ROM is relatively easy.
1. For a start, turn off your device and wait few seconds.
2. Secondly, press and hold volume down button with power button at the same time.
3. Then you have to keep pressing those buttons untill LG logo will flicker. Once it happens you can release the buttons and wait for next step.
4. And now on your screen there should appear this recovery mode menu:
5. To navigate here use volume buttons and power button to choose option. And this is it! You have reached your destination.
What does it for? In the past, a phone is more of a device used to make calls or text. However, it's much more than that.
Most Android devices are now defaulted with a fairly simple Recovery mode with features like Reboot System Now, Apply Update from ADB, Apply Update from External Storage, Wipe Data/Factory Reset, Wipe Cache Partition, Apply Update from Cache.
Just like a lot of other things with Android, even the Recovery Mode can be customized to do more things.