In the very old days of personal computing, the screen displayed just plain text. You had to type the instructions on the keyboard to tell your computer to do something. There wasn't even a mouse to click.
When Apple created the Mac they did it differently (and, no doubt, that's where the idea for the commercial—Think Different—was first spawned, although it came years later).
The Mac was designed to relate to you in a way that was familiar to anyone who works in an office, using a desktop. Common elements on the computer are shown as little pictures (icons) to serve as illustrations of the purpose of a specific item.
It's true that there are still computers today that are set up to work with a text (command-line) ...