Well, a test management tool is kind of like a way for people who are building something (like a website or an app) to make sure it works the way it's supposed to. It helps keep track of all the things that need to be tested, like different parts of the website or app and how they should work.
So, let's say you're building a new game app. One part of the game might be to have the player tap a button to make a character jump. You would use the test management tool to create a test case for this, which is basically a set of instructions for somebody to follow to make sure the jumping function works how it should. The instructions would say something like "tap the jump button and make sure the character jumps."
After you've created all the different test cases for all the different parts of the app, you would then use the tool to keep track of when each test is completed and if it passed or failed. If a test fails, it means something in the app isn't working how it should and needs to be fixed before the app is released to the public.
In summary, a test management tool is used to help make sure that things people build (like apps or websites) work the way they're supposed to. It does this by keeping track of all the different things that need to be tested and by keeping track of whether each test passed or failed.