Okay kiddo, a religious institute is a group of people (usually Catholic) who have chosen to live their lives together in a special way. They usually follow a set of rules called a "rule of life" that helps them live out their faith in a really special way.
These groups of people have different names, like monks, nuns, sisters, brothers, and friars. They often wear special clothes, like robes or habits, and might even shave their heads or wear special hats or scarves to show that they are part of their religious institute.
These groups usually live in a special place called a convent or monastery, which is kind of like a big house where they all live together. They spend a lot of time praying, studying the Bible, and doing good things for other people. They might also have special jobs, like cooking or teaching, that they do to help support their religious institute.
Being part of a religious institute is a really special calling, and it's not something that everyone does. But for the people who choose to do it, it can be a really beautiful way to live out their faith and serve others in a really special way.