Vegetables love coffee grounds and putting coffee grounds in your vegetable gardens soil will help the vegetables grow much better and stay healthier.
When you put coffee grounds in the soil of the vegetable garden the coffee grounds will encourage the growth of microorganisms in the soil and improve tilth.
This leads to a better growing vegetable garden but just don't put too much coffee grounds in the soil of the vegetable garden because then the soil could become to acidic which can kill the vegetable plants.
But putting a cup full into the soil every month or so is perfectly fine and you should see a good vegetable garden growing great healthy vegetables.