$2 companies are companies with no money. They often bring speculative law suits claiming tens or even hundreds of thousands of dollars in compensation for business opportunities which did not go ahead or which turned out badly.
Defending law suits brought by $2 companies is time consuming and expensive, especially when they go all the way to a court hearing which lasts 2 or more days. This applies of course to all law suits, but the particular problem with law suits brought by $2 companies is that if the defence is successful, the $2 company has no money to pay the legal fees the court orders to be paid by it - they simply go into liquidation to avoid payment.
Smart lawyers have a way of dealing with $2 companies bringing speculative law suits. They 'cut them off at the pass' by bring what is called a 'security for costs' motion.
What a security for costs motion does is to force the $2 company to pay into court the estimated amount of the legal fees the defence will incur in defending the law suit. And if the amount ordered is not paid, the law suit is 'stayed' (i.e. stopped), permanently.