How to I get rid of the black outlined box that tells me everything I am clicking on?

My friend pressed random keys on my computer, and now there is a rectangular square that is black and outlined with a white line, and whatever i put my mouse on, the black box tells me what i have clicked on. And then when I do click on something, it puts a black line around what I have clicked on, it is stressing me out and i have no idea how to get rid of it. Please help.