Okay kiddo, imagine there was a big group of people who wanted to build some really strong and safe places to live in case of danger, like forts. But building forts is hard work, and these people might not know how to do it themselves. So they asked someone else to help them, like a builder.
But the builder doesn't want to work for free, so they ask for some money in return for their hard work. This money is called a commission.
So in this case, the people who want to build forts ask someone to help them do it, and they pay that person a commission for their help. That person then organizes the building of the forts, making sure everything is done right.
Think of it like asking a friend to help you build a pillow fort in your room. You might give them $5 for their help, and they help you build the best pillow fort ever! The commission is like the $5 you gave your friend.