Reports is where the standard financial statements are produced, over whatever period you select.
What is available
Profit and loss — what you earned and spent, and what was left. See profit and loss.
Cash flow statement — money actually in and out, which is a different question from profit.
Balance sheet — what the business owns and owes at a point in time. See balance sheet.
Aging reports — receivables and payables grouped by how overdue they are.
Key numbers — the headline figures without a full statement around them.
Periods
Month to date, quarter to date, year to date, last month, last year, the last 30 or 90 days, or a custom range.
One habit is worth more than the rest: compare against the same period last year rather than against last month. Seasonal work makes month-to-month comparison close to meaningless — a slow January in a trade that is always slow in January is not a decline, and reading it as one leads to decisions made against the weather.
Where the numbers come from
Reports are built from the unified ledger, not copied out of your accounting software. Your accounting software's own reports are treated as a second opinion, and where the two disagree, the difference is shown to you rather than resolved silently.
That is a deliberate choice. Repeating another system's figures back to you would inherit its mistakes and present them with more confidence than they deserve.
Reading them honestly
A report is only as good as the categorisation behind it. If transactions are sitting uncategorised, expenses will be understated in the breakdown even though the totals are right. Clear the review queue before drawing conclusions from a P&L.