One way to describe a color is in terms of the intensity of three components: red, green, and blue. This descriptive form is known as RGB color space. (It’s called a color space because you can think of each of the three color components as representing a dimension in a 3D space.
The line object sends out a periodic series of numbers that progress to some new value over a certain amount of time. The input to line is a destination value (where it should eventually arrive), a transition time (how long it should take to get there), and a time interval between outputs (how often it should send out intermediate values along the way). The left part of this patch shows the use of line to generate integers that are used as pitches.