Imagine you have a bucket that you use to carry water from one place to another. However, you notice that there is a hole in the bottom of the bucket. This means that when you fill the bucket with water, some or all of the water comes out through the hole.
The hole could be small or big, and the water leaks out of it because there is no way to keep it inside the bucket. It's like a little door that opens up and lets the water escape.
In order to prevent the water from escaping, you need to patch up the hole or get a new bucket. If you don't do this, it can be frustrating because you won't be able to carry as much water as you want without it spilling out.
So, in short, a hole in your bucket means that water leaks out and you need to fix it so that you can carry water without losing any.