This Reddit thread kind-of explains it:
At the end of season 2, a California tech company, Hooli, has about
half of its contracts invalidated because they contained a non-compete
In yesterday's premiere, the tech company was able to make a large
amount of money by firing many of the employees with the invalidated
contracts (under other pretenses) as they would not have to pay them
severance packages or their vesting stock options. As such, the
company is able to take back control of all these stock options upon
the termination of these employees and make a decent profit.
They're paying off the employees to avoid them suing Hooli for getting terminated (I assume that the Hooli contracts are rather restrictive and that this works both ways), and it is actually a profitable move.
The thread does point out that this story-line is rather unrealistic, though, if not to say outright nonsense:
The judge's ruling would have been that the noncompete clause was too
broad and could not be enforced, not that the entire contract was
invalid as a result.
Also, it's quite far fetched that a tech giant would eagerly fire 1/3
of its engineers for this reason. Firstly, every tech company is
eternally starving for engineers. Secondly, the vesting of options
doesn't cost the company any money; the creation of the shares merely
dilutes the value of existing shares, so there is a cost to
shareholders but it's not going to reach even 5% of the current market
cap. The company realizes no revenue or increased margin as a result
of cancelling employee stock options.
It's one of those things where you just have to go with the show's logic, and not expect realism.