A more thorough explanation:

Concession bargaining is a type of negotiation between an employer and employees' representatives, usually a union, where the employees agree to give back some of the benefits they have previously gained, such as higher wages, better working conditions, or more benefits, in exchange for job security, such as protection against layoffs.

For example, a union may agree to a wage freeze or reduction in exchange for the employer's promise not to lay off any workers for a certain period. Another example is when employees agree to pay more for their health insurance to help the company save money and avoid layoffs.

Concession bargaining is often used during tough economic times when companies are struggling to stay afloat and need to cut costs. It can be a difficult decision for employees to make, as they have to give up some of their hard-earned benefits, but it can also help to save jobs and keep the company running.