There’s some confusion of terminology here. The word “lens” refers both to a single chunk of shaped glass (think of the single lens of a magnifying glass) and the tube-shaped device containing such lenses which you fasten to the end of your camera.

A lens element is a single piece of shaped glass or crystal. Camera lenses these days contain anywhere from 4 lens elements and up. They are frequently arranged in optical groups within the barrel. For that reason you may hear of a given lens having, say, 18 elements in 15 groups.

There are complex tradeoffs made in lens designs, so the number of elements and groups isn’t always the most reliable indicator of image quality. Simpler lenses with just a few elements tend to offer good results because they are so simple. Flare in particular (light reflection between elements in this case) is vastly reduced. However, wide angle and telephoto lens designs generally require more elements to correct for various optical aberrations.