Macroprudential regulation means rules designed to protect the financial system as a whole, so that the failure of one firm or a market-wide boom does not bring everything down. It is the rule-making side of macroprudential policy, which is explained in full on that page.
Typical tools include extra capital buffers for banks in a credit boom, limits on mortgage loan-to-value ratios and stress tests. They target systemic risk, the danger exposed by the 2008 financial crisis.