Anything velvety is smooth or soft in some way, like creamy chocolate or a soothing voice.
Have you ever felt velvet? It’s one of the smoothest fabrics. That’s why you can use the word velvety not only for things that are like velvet, but for anything smooth, whether it’s a texture, sight, or sound. The soft fur of a puppy is velvety. A lounge singer’s gentle voice is velvety. A drink that goes down easily is velvety. If something is rough, jarring, jagged, or sharp in some way, it’s the opposite of velvety.