Ok kiddo, have you ever seen a tower before? It's a tall structure with walls around it where people can go inside and look out at the world around them. Well, a watchtower is just like that, except it's specifically used for watching and keeping an eye out for certain things.
In the olden days, watchtowers were used to warn villages of incoming danger, like maybe an enemy army or wild animals. People would climb up the tower and look out at the surroundings, keeping an eye out for any potential threats.
Nowadays, some religions use the term "watchtower" to refer to a publication or a group of people who help keep an eye out for any issues or problems in the community. They might offer guidance or advice on how to handle certain situations and help people stay on the right path.
So, to sum it up, a watchtower is a tall structure or a group of people who keep an eye out for potential problems and help keep everyone safe.