In the context of business and labor relations, a strike is simply a situation in which the workers at a firm or firms refuse to work until certain demands are met. This is generally used as a last resort when a union cannot get what it wants through negotiation.
The point of a strike is to deprive the firm of revenue. Since the workers will not work, no new goods or services are being produced. The firm still has fixed costs that it must pay but is not producing and goods or services. The firm might also fear losing customers if it is unable to deliver things it has promised.
Strikes often do not work since the firm can often hold out without new revenues longer than workers can hold out without pay.
Refusing to perform labor in order to protest a policy, law, practice, etc. in order to be a blow to that business, industry, or economy so that the workers' demands are met or a compromise is reached.