In this problem
x -----> number of meals sold
y ----> profit
Remember that
the y-intercept is the value of y, when the value of x is zero
In this context
the y-intercept is the value of the profit when the restaurant begin or start to sell meals
In this case, the y-intercept is negative, which means when the restaurant started, there have a negative profit (loss) {the cost is greater than the revenue) because the number of meals sold is zero.