As the name suggests,
Salary received by employee is taxable under Income from Salaries
Example
Suppose a person gets flat salary of Rs 20000 p.m from his Company
Income from Salaries=20000*12=240000
Note:-
Salary is taxable under this head only if there is proper employer employee relationship
i.e. employee is working on payroll of company
If employee working on contract of company,then income not taxable under this head (It is taxable under Income from Other Sources)