The HSL panel allows you to affect individual colors in your image. HSL stands for Hue, Saturation, and Luminance.
You can use Hue to shift a color towards another color, for example, blue to purple or green. (Yes, you too can have purple skies!) Saturation is the intensity of color, so you can make your blues, for example, more rich or more faded out. Finally, Luminance is brightness. Use it to brighten or darken a particular color.
The HSL panel is one of my favorites, as I can often use it to make local changes to my images without going to the trouble of painting with the adjustment brush. For example, if I want to darken and saturate a sky more, as long as the sky is the only blue in the image, I can accomplish it very quickly with HSL.
I recently released a series of videos, “Lightroom Fundamentals: Workshop on DVD”. It consists of over 6 1/2 hours of training on 36 videos. You can watch my video on using the HSL panel here. (You can also watch my video on the adjustment brush here.) For the other 34 videos, you’ll have to buy the DVD! Click here for more information on the DVD.