Liquidity risk management is the set of policies and tools a bank or company uses to make sure it can meet its payment obligations as they fall due, without selling assets at fire-sale prices. It includes cash forecasting, holding a buffer of easily sold assets, spreading funding sources, setting limits and running stress tests. The risk it controls is explained in full in the entry on Liquidity Risk.
For banks, the main international rules come from Basel III: the Liquidity Coverage Ratio requires enough high-quality liquid assets to survive 30 days of stress, and the Net Stable Funding Ratio asks for stable funding over a one-year horizon. Day-to-day work sits with the treasury team under liquidity management and wider treasury management. Payment companies face the same problem on a smaller scale, for example when pre-funding accounts in several countries.