HSL components
Hue (0-360°): The color on the wheel. 0° = red, 120° = green, 240° = blue.
Saturation (0-100%): Vividness. 0% = gray, 100% = pure color.
Lightness (0-100%): Brightness. 0% = black, 50% = pure color, 100% = white.
Example: hsl(256, 90%, 65%) = A light, vivid purple
Why HSL is intuitive
To lighten a color, just increase lightness. To desaturate it, decrease saturation. No need to adjust three separate channels like RGB.
Limitations
HSL isn't perceptually uniform. Two colors with the same saturation/lightness can look very different. OKLCH solves this.