What does dollar liquidity mean?

Could you please clarify what exactly is meant by the term 'dollar liquidity' in the context of cryptocurrency and finance? I understand that liquidity generally refers to the ease of converting an asset into cash, but how does this specifically apply to dollars in the realm of digital currencies and their trading platforms? Is it related to the availability of dollars for trading or the demand for dollars in the market? And how does it impact the overall stability and valuation of cryptocurrencies?