Liquidity measures how fast you can access your invested money. A highly liquid investment can be converted to cash almost immediately and at a predictable price. A low-liquidity investment may take days or weeks to sell, or may require selling at a discount.
In the context of Egyptian savings products, liquidity exists on a spectrum: savings accounts are highly liquid (withdraw any business day), money market funds offer next-day or same-day liquidity, CDs are locked until maturity (or incur a penalty for early withdrawal), and physical gold requires finding a buyer and negotiating a price.