Imagine a super big city made up of multiple neighborhoods. Each neighborhood is made up of even smaller streets and houses. Now, imagine that instead of a city, we are talking about a really, REALLY big space area in the sky. This is called a supercluster.
The Hydra-Centaurus supercluster is a massive collection of galaxies (like neighborhoods) that are all very close together. It's one of the biggest superclusters we know of! Just like how you might have a group of friends who live on the same street, there are many galaxies in the Hydra-Centaurus supercluster that are all hanging out together.
This supercluster has galaxies that are located in different directions, but they're all close enough to each other to be considered part of the same big group. Scientists study the Hydra-Centaurus supercluster to learn more about how galaxies and space work. It's like exploring a really cool map of the stars!