No, not a dinner of leaves. It is one way of getting your plants to eat up their 'food' and a lot of people recommend it as a supplement to fertilizers in the ground.
I have always been a skeptic of foliar feed - why would the plants drink up through their leaves? Surely better to put it in the ground where their roots are.
Well I have changed my mind: the vines have grown a lot more strongly since they had a dose of foliar feed in their spray and the roses on the ends of the rows have also benefited. So now I am doing the same for all the roses and I think it is doing them good, especially when the weather is so dry they cannot 'drink up' anything through their roots.
PS I have ordered a new camera