Imagine that you are a teacher and you have some tasks to do every day. Maybe you need to grade papers, plan your lessons, and tidy up your classroom. You can't do all these things at the same time, so you make a plan. You decide to grade papers for 10 minutes, then plan your lessons for 10 minutes, and then tidy up for 10 minutes. After that, you start again with grading papers.
This is kind of like what a cyclic executive does. It is a way for a computer to handle different tasks or jobs and make sure they all get done on time. Just like you as a teacher, the computer can't do everything at once, so it needs to plan out how it will handle different jobs.
A cyclic executive divides the computer's time into cycles, kind of like how you divided your time into grading, planning, and tidying. Each cycle, the computer switches to a different task or job. For example, during one cycle, it might work on taking input from the keyboard. During the next cycle, it might work on processing that input. Then it might move on to displaying output on the screen during the next cycle.
The key thing to remember is that the computer keeps repeating these cycles over and over again, just like how you kept repeating your cycle of grading, planning, and tidying. This way, it doesn't forget about any tasks and can keep working on them all in turn. Like you needed to finish all your tasks before class started, the computer needs to finish all its tasks before moving on to the next cycle.