Don’t you love the metaphors in business terms? Liquid cash refers to assets that can change state easily, in this case, into cash. For an asset to be classified as liquid, it must have an established market where there is no shortage of buyers or sellers, so the asset price cannot be manipulated easily.
For example…
The global foreign exchange market is considered to be the most liquid in the world. As you can imagine, the volume of foreign currency exchanges across the world is huge, contributing to a free flowing stream of cash assets into and out of an economy. As the demand for foreign currency exchange is high, no individual can influence the exchange rate.