The Entities in an RDBMS represents a typical manual Register.
To understand the Manual Data and RDBMS data we will take the example of Employees register in a Company.
The employee register is in manual system is similar a Employee table in RDBMs
And like each entry in employee register is a similar a Row in the Employee table of RDBMS.
And each attribute of an employee register like name, dob, doj etc are similar Columns in the Employee table of RDBMS
And each value of attributes are similar the value of Columns in Employee table.