UPSC is a 3 stage   selection process involving Prelims, Mains and Interview which tests your personality test. Prelims has 2 Papers namely General Studies and CSAT.

General Studies has Current Events, History of India and Indian National Movement, Indian and World Geography, Indian Polity and Governance, Economic and Social Development, Environmental Ecology, Biodiversity and Climate Change and General Science.

CSAT has Comprehension, Interpersonal skills including communication skills, Logical Reasoning and Analytical ability, Decision making and problem solving, General Mental Ability, Basic numeracy and Data Interpretation.

Few books that can help you are:

Indian Polity for Civil Services by M. Laxmikanth

Indian Art and Culture by Nitin Singhania

Certificate Physical and Human Geography by Gog Cheng Leong

Oxford School Atlas by Oxford Publishers

Indian Economy by Ramesh Singh

Economic Survey by Ministry of Finance

India Year Book

A Brief History of Modern India by Rajiv Ahir