Preamble is an introductory statement that states the source of authority, date of adoption, guiding principles, etc. Also, it specifies character and values like sovereign, socialist, secular, democratic, republic, justice, liberty, equality, fraternity.
Republic: In a republic form of government, the head of the state is an elected person and not a heredity monarch
Liberty: It refers to the freedom on the activities of individuals.
Equality: All are equal in front of law.