The Little Man Computer (LMC) is a very simple computer that was made to help people learn about how computers work. It is made up of a few simple parts: an input, where you can enter commands and data; an output, where it can show you the results of calculations or commands you give it; some memory, where it stores data; and a few basic instructions for it to carry out.
Inputs, outputs and memory are like buildings blocks that computers need in order to run the instructions, or commands, you give them. Think of it like a playground: you can only play the games you know how to play, and you can only play with the pieces, or building blocks, you have.
The instructions are like a set of instructions for how to build something. Each instruction is like a single piece that you can use to build something bigger. For example, if you wanted to build a house, you would need to use instructions like: find a piece of wood, measure it, cut it, and so on. The Little Man Computer can be given instructions like those to do calculations or access data.
The Little Man Computer was made to help people understand the basics of computers, so they can then learn more advanced techniques and build complicated computers.