A swarm is like a big group of creatures that work together to achieve a goal. Think of a swarm of bees - there are lots of bees all working together to collect nectar and make honey.
In technology, a swarm is a group of computers that work together to run programs, just like the bees work together to collect nectar. Each computer in the swarm helps out by doing a small part of the work, and when all of them work together, they can do things much faster and more efficiently than a single computer could do on its own.
For example, let's say you wanted to download a movie. Instead of using just one computer to download the movie, you could use a swarm of computers. Each computer in the swarm would only download a small part of the movie, and then they would all work together to put the parts together into the full movie. This makes the download much faster and more reliable.
Overall, a swarm is just a group of things working together to achieve a goal, whether it's bees making honey or computers running programs.