Being involved means being a part of something or associated with it. If you volunteer on a team to clean up the playground, you're involved in making it a safer and more fun place for kids to play.
Involved is an adjective with many different uses. It can describe something difficult or complicated, as in "really involved instructions for putting together a plane model," or it describes relationships and partnerships, like when you’re involved with someone in a serious dating relationship or are involved in helping out as a tutor after school. You can be involved in more negative situations, too, as when a country is involved in spying on another or a group is involved in plotting a crime.