Hackers are people who like to build things with computers. They like figuring out how code works, and creating new code that does something interesting or new. They like exploring and pushing the boundaries of what computers can do - like watching a magician do a trick.
Hackers often gather together in online communities or in person at events called "hackathons" where they have a chance to show off their work and compete with each other. They like making and sharing cool programs with each other, and bragging about their achievements. It's like playing a game together, or having a sports match - only instead of playing sports, everyone is programming and trying to beat each other's high scores.