Okay, so you know when you play with blocks and build things like towers or houses? Java Modeling Language (JML) is like building plans for how someone else can make the same thing you did, but with a special language just for computer programs.
In computer programs, we have special "blocks" called code that tell the computer what to do. But sometimes, it can be hard to understand what someone else's code means because it's like they used different blocks or built their tower in a different way. JML helps make things easier to understand by giving us a special way to describe what the code is supposed to do.
It's like a map for someone who has never seen your block tower before. The map shows how tall the tower should be, where the windows and the doors are, and how many blocks you used for each part of the tower. JML is similar to that map, but for computer codes.
It helps other people know what the code is doing, so they can change or improve it without breaking anything inside. It's a special way to write notes about your code so that others can read it easily.
So, imagine building block towers without a plan, it would be really hard for someone else to figure out how to make the same tower. JML is the plan that makes it easier for other people or computers to understand what your code is supposed to do.