The three main statements, the income statement, balance sheet, and cash flow statement, are only the summary. Behind them sit dozens of pages called the notes, and this is where companies explain what the summary numbers actually contain. The notes disclose which accounting methods were chosen, how long assets are assumed to last, what sits inside catch-all lines like other liabilities, the details of debt and leases, expected losses on unpaid customer bills, and the reconciliation between official profit and any adjusted version the company promotes.
Almost every trick and choice described in this glossary is disclosed somewhere in the notes, which is precisely why almost nobody reads them and why the few who do have an edge. You find them in the annual report immediately after the financial statements. A practical habit for a beginner is not to read all of them, but to know they exist and to go looking whenever a number seems too good, too smooth, or too vague.