The classic RISC pipeline is a way of having a computer do tasks more quickly and efficiently. It is like having a factory with multiple workers doing different tasks. In a classic RISC pipeline, the computer sends instructions called tasks to the different workers in the factory. Each worker takes the instructions and does the task, like turning on a light or adding two numbers together. When the task is done, that worker passes it on to the next worker. This happens over and over until the final task is complete and the result can be given back.
So instead of having one person do all of the tasks, the classic RISC pipeline has multiple people all working together at the same time. This way, the computer can get its work done much quicker than if it had to do it all itself.