What is the meaning of 变现？ I have this sentence, but I'm not sure what '变现‘ means. I think it's 'assets', but baidu has 'realize' and 'liqidate'. Is '变现‘ an abbreviation for a longer phrase?

三是租赁行业，利用虚假身份证明，骗取汽车租赁公司汽车进行倒卖变现;

三是租赁行业，
The third kind is the rental car industry,

利用虚假身份证明
(they) use fake IDs,

骗取汽车租赁公司
(to) cheat rent-a-car companies

汽车进行倒卖变现;
car carry out resell at profit, realize cash/profit

they then sell the car to get cash.
变现 is a word by itself, not abbreviation, but it literally means 变成现金 (convert (assets) into cash), usually for the purpose of liquidation or realization, so commonly translated into 'liquidate' or 'realize'. The translation for the sentence in your question is correct.