A simple machine doesn't have a motor or a battery. It's just a clever shape. The shape lets you lift, push, or move something heavy with less force than you'd otherwise need. Humans have been using these for thousands of years.
A long bar resting on a point (the pivot). Push down on one end, and the other end goes up. The further from the pivot you push, the stronger the lift on the other side.
Archimedes (a wise Greek) said: "Give me a lever long enough, and I shall move the Earth."
Lifting a heavy box straight up = hard. Pushing it up a long, gentle slope = much easier — but you walk further. That's the deal: less force, more distance. Every simple machine does this trick in some way.
A pair of scissors is two levers + two wedges. A pencil sharpener is a wedge spinning on an axle. A bicycle is wheels, levers (the brakes), and gears (more wheels). Look around the kitchen — name a tool, and you'll find a simple machine inside.
You can't get something for nothing. To lift a heavy box, you must spend energy. But a simple machine lets you spread that work out — so you push less hard, but you push longer or further.
Six clever shapes. Thousands of inventions. They built every pyramid, every cathedral, every road.