With this adjustment layer, you can adjust the hue (color), saturation, and lightness of a specific range of colors in your image.

A selection allows you to isolate a part of your photo. There are many selection tools in photoshop, the most commonly used being the Rectangular Marquee Tool.

A layer mask is used to hide portions of a layer and reveal portions of whatever layer is below it. You can modify the mask by using the brush tool and painting in either black or white.