A ledger is kind of like a diary, but for money. It's a book for keeping track of expenses, profits, and other financial matters.
A ledger is an accounting journal used to keep track of money. Businesses — or their accountants — keep careful ledgers so they know how much money is coming in and going out. If you've ever heard the expression "cook the books" — meaning cheat financially by making things up — the "books" are ledgers. If you like numbers and money, maybe you should become an accountant so you can help people with their ledgers.
