eli5

ELI5 stands for "Explain Like I'm 5". It means explaining something in very simple terms so that a 5 year old would understand. For example, if someone asked "what is a computer?", you could explain it in ELI5 terms like this: "A computer is a machine that helps you do things on a screen. It can help you play games, do math, or look up answers to questions you have."