The education institution explained in the question refers to preschool, which is also known as kindergarten or nursery school. This type of school is dedicated to kids who have not yet qualified (age-wise) to enter first grade. It is usually from the age of 3 until 6 or 7, depending on the country.
It can be more academic, teaching children how to read and basic math – or more developmental, mastering the skills that they should be able to do at the age range stage that they are in.