Okay, imagine you are playing with blocks and you have a lot of them. You need to keep them in a line so they don't fall over. That's kind of like what line management is. It's when someone is in charge of keeping a lot of things in a neat and organized line so nothing gets messy or falls apart.
Now, let's say you have some friends who also want to play with the blocks. If everyone just starts putting blocks wherever they want, it could get really confusing and hard to keep track of. That's why someone needs to be in charge, like a teacher or parent, to tell everyone where to put the blocks and how to make sure they are all in a straight line.
That's kind of like what a line manager does at work. They are in charge of making sure everyone on their team is working together and doing their jobs correctly. They might give directions on how things should be done and check to make sure everything is running smoothly.
So basically, line management is all about keeping things organized and running smoothly, just like keeping blocks in a neat line.