The short answer
A monthly board package should include a balance sheet, an income statement comparing actual spending to budget, bank reconciliations for operating and reserve accounts, an accounts receivable (delinquency) report, a list of paid bills, and a manager's report on open maintenance items, violations, and upcoming projects.
Why it matters
Board members owe a fiduciary duty — see board member duties. A clear monthly package is how the board stays informed without doing the bookkeeping.