Our database comprises of a lot of different entities such as tables, stored procedures, functions, database owners and so on. To make sense of how all these different entities interact, we would need the help of schema. So, you can consider schema to be the logical relationship between all the different entities which are present in the database.
Once we have a clear understanding of the schema, this helps in a lot of ways:
Overall, you can consider a schema to be a blueprint for the database, which will give you the complete picture of how different objects interact with each other and which users have access to different entities.