The theory behind Object Relational Mapping and Object Relational Mapper is the same
Object Relational Mapping (ORM) is the ability for a program to look at your classes / class name and create corresponding tables for it in PostgreSQL
Example
If class name is Customer the table name would be customer. If the class has 4 properties then the table has 4 columns. If you create 5 objects of that class then the table will have 5 rows. If you create another object and try to save it it’ll create a new row in the database automatically