Sovereign: India is internally and externally sovereign – externally free from the control of any foreign power and internally, it has a free government which is directly elected by the people and makes laws that govern the people. No external power can dictate the government of India.
Republic: As opposed to a monarchy, in which the head of state is appointed on the hereditary basis for a lifetime or until he abdicates from the throne, a democratic republic is an entity in which the head of state is elected, directly or indirectly, for a fixed tenure. The President of India is elected by an electoral college for a term of five years. The post of the President Of India is not hereditary. Every citizen of India is eligible to become the President of the country.
Socialist: “Socialism” as an economic philosophy where means of production and distribution are owned by the State. India adopted Mixed Economy, where apart from the state, there will be private production too. Socialism as a social philosophy stresses more on societal equality.