Selective color photography is a process of photo manipulation in which a photographer will convert a photograph from colour to black & white yet leaving an "accent" or partial colour in a defined area of the image
Three sliders are in the Hue/Saturation dialog box.
Hue: Shifts all the colors clockwise or counterclockwise around the color wheel, depending on the direction you move the slider.
Saturation: Increases or decreases the richness of the colors in an image.
Lightness: Modifies the brightness values.