Computer Basics
Computers are electronic devices that can perform calculations using instructions from software. All computers need a processor, some memory and a way for a user to communicate with the computer, like a keyboard, mouse, and display. Many devices have built-in computers. Some common ones you may already use are a microwave, a smartphone, and your car. As long as the hardware includes a brain and a way for the brain to perform calculations, it's a computer.
The computer is the hardware, while the software is the instructions which tell the computer what to do. If you were in your kitchen making a meal, you would be the computer and the recipe which you're following would be the software.
The recipe tells you what ingredients and utensils you need to use to physically prepare the meal. Follow one recipe and you might have a sandwich, follow a different one and you'd end up with a salad. You're the same person, but you're following different instructions for each meal. When computers run different software, they are following different instructions. Without software, your computer would be an expensive paperweight.