Google glass is a wearable computer by Google which has the ability to capture the world as you see it in real time and share it to anyone you want.
Google glass is like a head up display in a fighter aircraft, which can present information such as directions how to get somewhere right in front of you, superimposed on the real world.
It gives you all the information you need such as translations, flight times etc either on the display or in your ear without the device getting in the way of your life, or without people knowing what you are doing.
below is a quote from Google about Google glass
"We started Project Glass to build technology that’s seamless, beautiful and empowering. To share the world through your eyes. To get answers and updates, instantly. To be there when you need it, and out of your way when you don’t."