Volado is the leaf nearest the ground. It gets less sun, stays thinner, and lights more easily than the leaves above it. In the bunch it helps keep the cigar lit, because ligero burns slowly and tends to go out.
It has some flavor, but it is not the main source of flavor. A cigar made only of volado would burn well but taste of very little. A cigar with no volado can be hard to keep lit, especially in a large ring gauge. Factories sort volado as carefully as the more valuable grades, because a leaf that burns badly can ruin an expensive wrapper.
Viso grows above it, and seco above that. These names describe position on the plant; they are farming terms, not marketing terms.