Answer:
This means that the wage of $12 per hour is the wage in which labor supply (the workers) and labor demand (that is demanded by firms) meet and reach market equilibrium.
If the wage was raised, for example to $13 or $14 per hour, there would be an oversupply of fast food workers, leading to unemployment. And if the wage was lowered, for example to $12 or $11 per hour, there would be a higher demand for workers than the supply, leading to a labor shortage for some fast food restaurants.
