Hi, I am doing business or profession, I need to keep proper books (proper means the ability to identify and track), record of my incomes/ bills raised by me and my expenses. At end of year I prepare accounts, which means my profit and loss statement (showing under various categories My incomes and My expenses)and my balance sheet (showing under various categories, My Assets and My Liabilities).
Books just means a record of what I got and what I paid, we call it cash book and bank book, my Journal (if I do accrual below rather than cash -see further), expense vouchers, my receipt bills, my assets bought and my liabilities paid. I just need to keep a track (in a defined way) of what I am doing.