An executive officer is like the boss of a very important group, like a big company or a government organization. They are in charge of making sure everything runs smoothly and that everyone working together is doing a good job.
Think of it like a game of pretend where you and your friends are building a big castle out of blocks. If you were the executive officer, you would be the one in charge of making sure everyone has the right blocks, that they are building in the right place, and that everyone is working together to make the castle look awesome.
The executive officer has a really big job and has to make important decisions about how the group should work and what goals they should try to achieve. They have to be really good at managing people and making sure everyone is happy and getting along. It's kind of like taking care of a big family, but at work or in an important organization.