You'll notice it's called “overshoot_spline” inside “sop_pins”.
This is a spline VOP, which generates a spline (that doesn't show up in viewports) based on input keypoints. Those constants that are connected into the “overshoot_spline” node are the keypoints (not animation keypoints) which are used to create a math function. In this case, a function that starts at 0, goes up to 1.2, then settles at 1. This spline (which is a math function) doesn't show up anywhere because it's used to control a parameter, and doesn't directly correspond to something visual.
Hope that makes a little more sense. I'm slowly getting there with Houdini too. It has a very steep learning “spline”
The “print” module (is module the right word here??) is in VEX Builder and is used to print values out somewhere, but if you switch on “output text to console”, weird stuff happens.