A ligero leaf is harvested late, after the lower primings have already come off the plant. It has had more days in the sun. The veins are heavier. The lamina holds more oil. In the curing barn it dries slower; in the pilón it runs hotter and wants more turns.
Rollers treat it as fuel for body, not as the whole cigar. Too much ligero in a thin vitola like a lancero can make a stubborn burn. A toro or robusto has more room to bury a strip of it inside seco and volado. See ligero for how that leaf is used in the bunch.
This is agricultural language, not tasting language. A ligero leaf can smoke earthy, sweet, or peppery depending on seed, soil, and time. The priming name does not invent those flavors.