Explanation:

The words ‘Socialist’, Secular’ and ‘Unity and Integrity of the Nation’ were added to the Preamble of constitution of India by the 42nd amendment.
Socialism is an economic and political system where the ways of making a living (factories, offices, etc.) are owned by the workers who run them and the people who depend on them. ... Socialists believe that everything in society is made by the cooperative efforts of the people and citizens.
Secular things are not religious. Anything not affiliated with a church or faith can be called secular. Non-religious people can be called atheists or agnostics, but to describe things, activities, or attitudes that have nothing to do with religion, you can use the word secular.
The Preamble declares that fraternity has to assure two things—the dignity of the individual and the unity and integrity of the nation. The word 'integrity' has been added to the Preamble by the 42nd Constitutional Amendment (1976).