You just bought Nexus 4 and you don't know anything about Android operating system, so I will guide you through literally first steps on this great phone.
Airplane mode on a phone is when you disable all the active connections like WiFi, bluetooth and mobile network. Let's see how to enable it so you don't need to turn off your phone on an airplane.
If you are tired and annoyed by the app requests and notifications your friends keep sending on Facebook, this is how you get rid of them without having to unfriend your friends.
If you'r a fast typer and don't pay much attention to spelling or English isn't your first language? No biggie, you can get a spell checker add-on for Firefox.