Sure. Thank you for the question.
A wet lease is when a company leases not only an aircraft but a flight crew as well. Often all of the associated expenses are covered in a single transaction rather than by leasing an aircraft and hiring a crew separately.
If this is done improperly, it can disrupt the labour market and undermine collective bargaining for unionized groups, because it's basically contracting out what could be—and in some cases, should be—work that belongs to the bargaining unit.