Gap analysis is kind of like a treasure hunt, but instead of finding gold or a toy, you're looking for things at school, home or work that are missing or aren't working very well. When you find something that's not right or missing, you write it down on a list.
Then, you make another list of what should be there or what needs to be fixed. For example, if you notice that your school doesn't have a playground, you write that down on the first list. On the second list, you write down that the school needs a playground.
This is called the "gap", because there is a difference between what is there and what should be there. Once you've found all the gaps, you can figure out how to fill them in or fix them so that things work better.
This is important in many different areas, like in business or government, because it helps people figure out what's not working and what needs to be done to make things better. It's kind of like a map or a plan to make things better.