Liquid assets are assets that resemble cash, because they can easily be converted into cash and used to buy other assets. The idea seems to be that there are a lot of liquid assets lying around, and that they are being used to get money to bid up the prices of stocks, housing, land, art, etc.
流动资产是与现金类似的资产，因为它们可以被很容易地转换成现金并且用来购买其他资产。大家似乎认为存在大量的流动资产，并且它们正被用来换成钱来哄抬股票、住房、土地、艺术品等的价格。